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THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

DAVIS 


Digitized  by  tine  Internet  Arciiive 

in  2007  with  funding  from 

IVIicrosoft  Corporation 


littp://www.archive.org/details/botanicaltextbooOOgrayrich 


d?ucy  . 


♦    X 


t 


THE 


BOTANICAL  TEXT-BOOK, 


INTRODUCTION   TO    SCIENTIFIC    BOTANY, 


BOTH   STRUCTURAL   AND    SYSTEMATIC. 


FOR  COLLEGES,  SCHOOLS,  AND  PRIVATE  STUDENTS. 


THIRD    EDITIOJff, 

REWRITTEN      AND      ENLARGED. 


By  ASA   GRAY,  M.  D., 

FISHER   PHOFESSOR   OP   NATURAL  HISTORY   IN   HARVARD    UNIVERSITY. 


NEW   YORK: 

GEORGE  P.  PUTNAM. 

1850. 

LIBRARY 

UNIVERSITY  OF  CALIFORNIA 


Entered  accordiug  to  Act  of  Congress,  in  the  year  1850,  by 

George    P.  Putnam, 

in  the  Clerk's  Office  of  the  District  Court  of  the  Southern  District  of  New  York. 


CAMBRIDGEI 
METCALF  AND  COMPANY, 

PRINTERS  TO  THE  UNIVERSITY. 


THE 


BOTANICAL   TEXT-BOOK 


95GC3 


PREFACE. 


This  compendious  treatise  is  designed  to  furnish  classes 
in  our  schools  and  colleges  with  a  suitable  text-book  of 
Structural  and  Physiological  Botany,  as  well  as  private 
students  with  a  convenient  introductory  manual,  adapted 
to  the  present  condition  of  the  science.  The  favor  with 
which  the  former  editions  have  been  received,  while  it  has 
satisfied  the  author  that  the  plan  of  the  work  is  well 
adapted  to  the  end  in  view,  has  made  him  the  more  desir- 
ous to  improve  its  execution,  and  to  render  it  a  better  ex- 
ponent of  the  present  state  of  Physiological  Botany.  To 
this  end  the  structural  and  physiological  part  of  the  work 
has  been  again  almost  entirely  rewritten  for  this  third  edi- 
tion, and  much  enlarged.  The  chapter  on  the  elementary 
structure  of  plants,  or  vegetable  anatomy,  the  sections  on 
the  internal  structure  of  the  stem,  on  phyllotaxis  and  its 
relations  to  floral  structure,  and  on  the  symmetry  and 
morphology  of  the  flower,  may  be  particularly  adverted  to, 
as  having  been  altogether  recast  and  greatly  extended. 
The  want  of  space  and  time  has  prevented  a  similar  exten- 
sion of  the  systematic  part  of  the  work,  especially  of  the 
Illustrations  of  the  Natural  Orders.  This  portion,  however 
amplified,  could  never  take  the  place  of  a  Flora,  or  System 
1* 


PREFACE. 


of  Plants,  but  is  designed  merely  to  give  a  general  idea  of 
the  distribution  of  the  vegetable  kingdom  into  families, 
&c.,  with  a  cursory  notice  of  their  structure,  distribution,, 
properties,  and  principal  useful  products.  The  student 
who  desires  to  become  acquainted,  as  he  should,  with  the 
plants  that  grow  spontaneously  around  him,  will  neces- 
sarily use  some  local  Flora,  such,  for  example,  as  the  au- 
thor's Manual  of  the  Botany  of  the  Northern  United  States. 
For  particular  illustrations  the  botanist  may  advantageous- 
ly consult  the  Genera  of  the  Plants  of  the  United  States^ 
illustrated  hy  Figures  and  Analyses  from  Nature^  of  which 
two  volumes  have  been  published. 

By  permission  of  the  Secretary  of  the  Smithsonian  In- 
stitution, the  figures  No.  20-22,  33,  37,  105-110,  130- 
133,  135,  136,  159,  160,  and  161-164,  are  copied  from 
original  sketches  made  for  the  Introduction  to  a  Report  on 
the  Trees  of  the  United  States^  now  in  preparation  by  the 
author,  for  that  Institution. 

Harvard  University,  Cambridge,  April,  1850. 


CONTENTS. 


PAGE 

INTRODUCTION.  —  General  Survey  of  the  Science         .  13 


PAET     I. 
STRUCTURAL  AND  PHYSIOLOGICAIi  BOTANY. 

CHAPTER  I.     OF  THE  ELEMENTARY  STRUCTURE  OF 

PLANTS 17 

Sect.  I.  Of  Organization  in  General  ....  17 

The  Elementary  Constitution  of  Plants           .          .         .  17 

Their  Organic  Constitution         ......  18 

Distinctions  between  Minerals  and  Organized  Beings       .  19 
Individuals  and  Species     .          .          .          .          .     -     .          .20 

Life 21 

Difference  betv^reen  Vegetables  and  Animals        .  .         .22 

Sect.  II.     Of  the  Cells  and  Cellular  Tissue  of  Plants 

IN   General          ......  23 

Cellular  Structure •   .  23 

Formation  and  Development  of  Cells     .          ...  26 

Multiplication  of  Cells 29 

Gemmation  or  Budding  of  Cells    .....  32 

Elongating  and  Ramifying  Cells         .  .  .  .  .33 

Circulation  in  Young  Cells     ......  33 

Permeability  and  Imbibition  (Endosmosis)           ...  34 

Growth  of  Cell-Membrane  interstitially           ...  35 

Thickening  by  Deposition           ......  36 

Markings  of  the  Walls  of  Cells      .....  38 

Free  Gelatinous  Coils  in  Cells            .         .          .          .         .  42 


yiii  CONTENTS. 

Sect.  III.     Of  the  Kinds  or  Transformations  of  Cellu- 
lar Tissue ^^ 

Parenchyma ^^ 

Prosenchyma,  Woody  Tissue 44 

Bast  Tissue 46 

Vascular  Tissue  or  Vessels 48 

Interlaced  Fibrilliform  Tissue 52 

Laliciferous  Tissue ;  52 

Intercellular  System S  54 

Epidermal  System 55 

Sect.  IV.     Of  the  Contents  of  the  Tissues        ,         .  56 

Sap 56 

Proper  Juices          .....*..  57 

Starch 57 

Vegetable  Jelly 59 

Sugar,  Wax,  Chlorophyll 60 

Alkaloids        .........  61 

Vegetable  Acids          ........  61 

Crystals  or  Raphides      .......  62 

Silex 63 

CHAPTER  11.  OF  THE  GENERAL  MORPHOLOGY  OF 

THE  PLANT 64 

The  Individual  Plant 64 

Plants  of  a  Single  Cell 64 

Plants  of  a  Single  Row  of  Cells 68 

Spores,  Conjugation        .......  69 

Plants  of  a  Tissue  of  Cells 70 

Plants  with  a  Distinct  Axis  and  Foliage            ...  71 

Thallophytes  and  Cormophytes  .....  73 
Cellular  and  Vascular  Plants  .  .  ,  .  .73 
Cryptogamous  or  Flowerless  Plants     .         .  '       .         .         .74 

Phaenogamous  or  Flowering  Plants           ....  75 

Development  of  the  Plant  from  the  Embryo        .         c         .  77 

Organs  of  Vegetation 79 

CHAPTER  in.     OF  THE  ROOT  OR  DESCENDING  AXIS  80 

The  Primary  Root           ....'.,,  80 

Annuals,  Biennials,  and  Perennials 85 

Secondary  Roots 87 

Aerial  Roots       .........  87 

Epiphytes      .........  89 

Parasites 90 


CONTENTS. 


XI 


Coalescence  of  Parts 
Adnation        .         .         .         .         . 
Irregularity         .... 
Suppression  or  Abortion 
Abnormal  States  of  the  Receptacle 

Sect.  V.     The  Floral  Envelopes 
Their  Development  . 
Estivation  or  Praefloration 
The  Calyx         .... 
The  Corolla 


Sect.  VI.     The  Stamens      .... 
The  Filament  and  Anther       ... 
The  Pollen " 

Sect.  VII.     The  Pistils  .         .         .  . 

The  Placenta    ...... 

The  Carpel  or  Carpidium        ... 
The  Compound  Pistil  .... 

Modes  of  Placentation    .... 

Gynaecium  of  Gymnospermous  Plants 

Sect.  VIII.     The  Ovule 

Sect.  IX.     Fertilization     .... 

Action  of  the  Pollen       .         ^         .         . 

Formation  of  the  Embryo 

CHAPTER  X.     OF  THE   FRUIT 

Sect.  I.       Its    Structure,  Transformations, 
cence  .... 

Sect.  II.     Its  Kinds    ..... 

CHAPTER   XL     OF   THE    SEED 

Sect.  I.     Its  Structure  and  Parts 
The  Nucleus  and  Albumen     . 
The  Embryo      ...... 

Sect.  II.     Germination    .... 
^*^  Cryptogamous  or  Flowerless  Plants        .... 

CHAPTER  XII.     OF  THE  SPONTANEOUS  MOVEMENTS 
WHICH   PLANTS   EXHIBIT. 
Special  Directions  ....... 

The  Sleep  of  Plants  .         .         .          .         . 


Dehis- 


340 
340 
342 


Xii  CONTENTS. 

Movements  from  Irritation      ......  344 

Automatic  Movements 345 

Free  Movements  of  Spores 345 


PART  II. 

SYSTEMATIC  BOTANY. 

CHAPTER   I.     OF    CLASSIFICATION    AND    ITS    PRIN- 
CIPLES       349 

Individuals  and  Species     .......  350 

Varieties  and  Races         .......  351 

Hybrids  or  Cross-breeds     .         .         .   '      ,         .         .         .  352 

Genera  .........  352 

Orders  or  Families     ........  353 

Suborders,  Tribes,  &c.  .......  354 

Classes •      .         .354 

Characters 354 

CHAPTER     n.      OF     THE     ARTIFICIAL     SYSTEM     OF 

LINN^US 356 

CHAPTER  in.     OF  THE   NATURAL   SYSTEM  .         .  361 

CHAPTER   IV.     ILLUSTRATIONS    OF    THE    NATURAL 

ORDERS 371 

APPENDIX. 

Signs  and  Abbreviations  ......  505 

Directions  for  Collecting  and  Preserving  Plants,  «S6c.  506 

INDEX  AND  General  Glossary  of  Botanical  Terms       .         .  508' 


CONTENTS.  IX 

CHAPTER  IV.     OF   THE    STEM    OR  ASCENDING  AXIS  93 
Sect.  I.      Its    General    Characteristics    and    Mode    of 

Growth         .......  93 

Nodes  and  Internodes 94 

Buds 95 


Sect.  II.     Ramification        . 98 

Branches        .........  98 

Adventitious  and  Accessory  Buds        .....  100 

Propagation  from  Buds  .......  103 

Sect.  Ill,     The  Kinds  of  Stem  and  Branches          .         ,  103 

Herbs,  Slirubs,  and  Trees 103 

Stolons,  Runners,  Tendrils,  Thorns,  &c.     ....  104 

Subterranean  Modifications      ......  106 

Rhizoma  or  Rootstock         .         .         .         .         .         .         .  107 

Tuber,  Corm 108 

Bulbs  and  Bulblets ,         .         .  110 

Sect.  IV.     The  Internal  Structure  of  the  Stem       .  112 

Sect.  V.     The  Exogenous  or  Dicotyledonous  Stem         ,  114 

The  First  Year's  Growth 115 

The  Pith  and  Medullary  Sheath 116 

The  Wood 117 

The  Bark           . .  118 

The  Second  Year's  Growth  in  Diameter          .         .         .  121 

Annual  Increase  of  the  Wood    ......  122 

Sap-wood  and  Heart-wood 124 

Sect.  VI.     The  Endogenous  or  Monocotyledonous  Stem  129 

Sect.  VII.     Of  the  Theoretical  Structure  of  the  Stem  131 

Origin  of  the  Wood        .......  131 

The  Plant  a  Composite  Being     ......  137 

Phytons 139 

CHAPTER  V.     OF   THE   LEAVES 140 

Sect.  I.     Their  Arrangement 140 

Phyllotaxis         .         '. .141 

Vernation  or  Praefoliation         ...•••  1^1 

Sect.  II.     Their  Structure  and  Conformation        .         .  152 

Anatomy  of  the  Leaf     .......  1^2 

Stomata l^'' 

Development  of  the  Leaf 1"" 


CONTENTS. 

The  Forms  of  Leaves 160 

Compound  Leaves           .......  168 

The  Petiole  or  Leafstalk 171 

Phyllodia 172 

Ascidia,  or  Pitchers 173 

Stipules          .         .         * 174 

Sect.  IIL     Their  Death  and  Fall;  Exhalation,  etc.    .  175 

Duration  of  Leaves 175 

Fall  of  the  Leaf 176 

Death  of  the  Leaf          . 177 

Exhalation  from  the  Leaves        ......  179 

Rise  of  the  Sap      .         . 179 

CHAPTER   VL      OF   THE    FOOD    AND    NUTRITION   OF 

PLANTS 181 

Sect.  I.     The   General  Physiology  of  Vegetation      .  181 

Sect.  II.      The    Food    and    Elementary    Composition    of 

Plants 183 

Sect.  III.      Assimilation,   or  Vegetable   Digestion,   and 

its  Results 194 

CHAPTER   VII.      OF    FLOWERING    AND    ITS    CONSE- 
QUENCES             209 

Flowering  an  Exhaustive  Process        .....  209 

Evolution  of  Heat 211 

Plants  need  a  Season  of  Rest     ......  213 

CHAPTER   VIII.     OF   THE    INFLORESCENCE       .         .  215 

Indefinite  or  Indeterminate  Inflorescence    ....  216 

Definite  or  Determinate  Inflorescence     ....  222 

CHAPTER   IX.     OF   THE   FLOWER     .....  227 

Sect.  I.     Its  Organs  or  Component  Parts     .         .         .  227 

Sect.  II.     Its  Theoretical  Structure  or  General  Mor- 
phology         230 

Sect.  III.     Its  Symmetry     .......  238 

Alternation  of  the  Floral  Organs     .....  241 

Position  as  Respects  the  Axis  and  Bract      ....  243 

Sect.  IV.     The  Various  Modifications  of  the  Flower  244 

Augmentation  of  the  Floral  Circles    .....  248 

Chorisis  or  Deduplication 249 


THE 


BOTANICAL    TEXT-BOOK 


INTRODUCTION. 

GENERAL    SURVEY    OF    THE    SCIENCE. 

1.  Botany  is  the  Natural  History  of  the  Vegetable  Kingdom. 
The  vegetable  kingdom  consists  of  those  beings  (called  plants) 
which  derive  their  sustenance  from  the  mineral  kingdom,  that  is 
from  the  earth  and  air,  and  create  the  food  upon  which  aninrials 
live.  The  proof  of  this  proposition  will  be  hereafter  afforded,  in 
the  chapter  upon  the  food  and  nutrition  of  plants.  The  vegetable 
kingdom,  therefore,  occupies  a  position  between  the  mineral  and 
the  animal  kingdoms.  Comprehensively  considered.  Botany  ac- 
cordingly embraces  every  scientific  inquiry  that  can  be  made 
respecting  plants,  —  their  nature,  their  kinds,  the  laws  which  gov- 
ern them,  and  the  part  they  play  in  the  general  economy  of  the 
world,  —  their  relations  both  to  the  lifeless  mineral  kingdom  below 
them,  from  which  they  draw  their  sustenance,  and  to  the  animal 
kingdom  above,  endowed  with  higher  vitality,  to  which  in  turn 
they  render  what  they  have  thus  derived. 

2.  There  are  three  aspects  under  which  the  vegetable  world 
may  be  contemplated,  and  from  which  the  various  departments  of 
the  science  naturally  arise.  Plants  may  be  considered  either  as 
individual  beings ;  or  in  their  relations  to  each  other,  as  collec- 
tively constituting  a  systematic  unity,  that  is,  a  vegetahle  kingdom; 
or  in  their  relations  to  other  parts  of  the  creation,  —  to  the  earth, 
to  animals,  to  man. 

3.  Under  the  first  aspect,  namely,  when  our  attention  is  direct- 
ed to  the  plant  as  an  individual,  we  study  its  nature  and  structure, 

2 


14  INTRODUCTION. 

the  kind  of  life  with  which  it  is  endowed,  the  organization  through 
which  its  life  is  manifested;  —  in  other  words,  how  the  plant  lives 
and  grows,  and  fulfils  its  destined  officest  This  is  the  province  of 
PHYSIOLOGICAL  BOTANY.  It  comprises  a  knowledge,  1st, 
of  the  intimate  structure  of  the  plant,  the  minute  machinery- 
through  which  its  forces  operate  ;  —  this  is  the  special  field  of 
Vegetable  Anatomy;  —  and,  2d,  of  the  plant's  external  con- 
formation, the  forms  and  arrangement  of  the  several  organs  of 
which  it  is  composed,  the  laws  of  symmetry  which  fix  their  posi- 
tion, and  the  modifications  they  respectively  undergo,  whether  in 
diflferent  species,  under  diflTerent  conditions,  or  in  a  single  individ- 
ual during  the  successive  stages  of  its  development.  This  branch 
of  the  science  is  variously  called  Organography  (the  study  of  the 
organs),  or  Morphology  (the  study  of  their  various  modifications 
in  form,  according  to  the  office  they  are  destined  to  subserve),  or 
Structural  Botany  ;  and  nearly  corresponds  with  what  is  termed 
Comparative  Anatomy  in  the  animal  kingdom.  Under  both  these 
aspects,  (whether  we  study  their  interior  structure,  or  their  external 
conformation,)  the  plant  is  viewed  as  a  piece  of  machinery,  adapt- 
ed to  efiect  certain  ends.  The  study  of  this  apparatus  in  action, 
endowed  with  life,  and  fulfilling  the  purposes  for  which  it  was 
constructed,  is  the  province  of  Vegetable  Physiology,  strictly  so 
called, 

4.  The  subjects  which  Physiological  Botany  embraces,  namely, 
Vegetable  Anatomy,  Organography,  and  Physiology,  therefore, 
spring  naturally  from  the  study  of  vegetables  as  individuals,  — 
from  the  contemplation  of  an  isolated  plant  throughout  the  course 
of  its  existence,  from  germination  to  the  flowering  state,  and  the 
production  of  a  seed  like  that  from  which  the  parent  stock  origi- 
nated. These  branches  would  equally  exist,  and  would  form  a 
highly  interesting  study,  (analogous  to  human  anatomy  and  physi- 
ology,) even  if  the  vegetable  kingdom  were  restricted  to  a  single 
species. 

5.  But  the  science  assumes  an  immeasurably  broader  interest 
and  more  diversified  attractions,  when  we  look  upon  the  vegetable 
creation  as  consisting,  not  of  wearisome  repetitions  of  one  particu- 
lar form,  in  Uself  however  perfect  or  beautiful,  but  as  composed  of 
thousands  of  species,  all  constructed  upon  one  general  plan,  in- 
deed, but  this  plan  modified  in  each  according  to  the  rank  it  holds, 
and  the  circumstances  in  which  it  is  placed.     This  leads  to  the 


INTRODUCTION.  15 

second  great  department  of  the  science,  namely,  SYSTEMATIC 
BOTANY,  or  the  study  of  plants  in  their  relations  to  one  another ; 
as  forming  a  vegetable  kingdom^  which  embraces  an  immense 
number  of  species,  more  or  less  like  each  other,  and  there- 
fore capable  of  being  grouped  into  kinds  or  genera^  into  orders^ 
classes^  &c. 

6.  Thus  arises  Classification,  or  the  arrangement  of  plants  in 
systematic  order,  so  as  to  show  their  relationships ;  also  Special 
Descriptive  Botany,  embracing  a  scientific  account  of  all  known 
plants,  designated  by  proper  names,  and  distinguished  by  clear 
and  exact  descriptions.  Necessarily  connected  with  these  depart- 
ments is  Terminology  or  Glossology,  which  relates  to  the  appli- 
cation of  distinctive  names  or  terms  to  the  several  organs  of  plants, 
and  to  their  numberless  modifications  of  form,  &c.  The  accom- 
plishment of  this  object  renders  necessary  a  copious  vocabulary  of 
technical  terms ;  for  the  current  words  of  ordinary  language  are 
not  sufficiently  numerous  or  precise  for  this  purpose.  New  terms 
are  therefore  introduced,  for  accurately  expressing  the  great  vari- 
ety of  new  ideas  to  which  the  exact  comparison  of  plants  gives 
rise ;  and  thus  a  technical  language  has  gradually  been  formed, 
in  this  as  in  every  other  science,  by  which  the  botanist  is  able  to 
describe  the  objects  of  his  study  with  a  perspicuity  and  brevity  not 
otherwise  attainable. 

7.  These  several  departments  include  the  whole  natural  history 
of  the  vegetable  kingdom,  considered  independently.  But,  under 
a  third  point  of  view,  plants  may  be  contemplated  in  respect  to 
their  relations  to  other  parts  of  the  creation  ;  whence  arises  a  se- 
ries of  interesting  inquiries,  which  variously  connect  the  science 
of  Botany  with  Chemistry,  Geology,  Physical  Geography,  &c. 
Thus,  the  relations  of  vegetables  to  the  mineral  kingdom,  consid- 
ered as  to  their  influence  upon  the  soil  and  the  air,  —  as  to  what 
vegetation  draws  from  the  soil,  and  what  it  imparts  to  it,  what  it 
takes  from  and  what  it  renders  to  the  air  we  breathe  ;  and,  again, 
the  relations  of  the  vegetable  to  the  animal  kingdom,  considered  as 
furnishing  sustenance  to  the  latter,  and  the  mutual  subservience  of 
plants  and  animals  in  the  general  economy  of  the  world,  —  all 
these  inquiries  belong  partly  to  Chemistiy,  and  partly  to  Vegeta- 
ble Physiology ;  while  the  practical  deductions  from  them  lay  the 
foundation  of  scientific  Agriculture,  &c.  The  relations  of  plants 
to  the  earth,  considered  in  reference  to  their  natural  distribution 


16  INTRODUCTION. 

over  its  surface  and  the  laws  that  regulate  it,  especially  as  con- 
nected with  the  actual  distribution  of  those  natural  agents  which 
chiefly  influence  vegetation,  such  as  heat,  light,  water,  &c.,  (in 
other  words,  with  climate,)  give  rise  to  Geographical  Botany,  a 
subject  which  connects  Botany  with  Physical  Geography.  Under 
the  same  general  department  naturally  falls  the  consideration  of 
the  changes  which  the  vegetable  kingdom  has  undergone  in  times 
anterior  to  the  present  state  of  things,  as  studied  in  their  fossil  re- 
mains, (a  contribution  which  Botany  offers  to  Geology,)  as  well  as 
of  those  changes  which  man  has  effected  in  the  natural  distribution 
of  plants,  and  the  alterations  in  their  properties  or  products  which 
have  been  developed  by  culture. 

8.  Of  these  three  great  departments  of  the  science,  that  of 
Physiological  Botany,  forming  as  it  does  the  basis  of  all  the  rest, 
first  demands  the  student's  attention. 


PAUT    I. 

STRUCTURAL  AND  PHYSIOLOGICAL  BOTANY. 


9.  The  principal  subjects  which  belong  to  this  department  of 
Botarry  may  be  considered  in  the  most  simple  and  natural  order, 
by  tracing,  as  it  were,  the  biography  of  the  vegetable  through  the 
successive  stages  of  its  existence,  — the  development  of  its  essen- 
tial organs,  root^  stem,  and  foliage,  the  various  forms  they  assume, 
the  offices  they  severally  perform,  and  their  combined  action  in 
carrying  on  the  processes  of  vegetable  life  and  growth.  Then  the 
ultimate  development  of  the  plant  in  flowering  and  fructification 
may  be  contemplated,  —  the  structure  and  office  of  the  flower,  of 
the  fruit,  the  seed,  and  the  embryo-plant  it  contains,  which,  after 
remaining  dormant  for  a  time,  is  at  length  aroused  by  the  influence 
of  common  physical  agents,  (warmth,  air,  and  moisture  conjoined,) 
and  in  germination  developes  into  a  plant  like  the  parent ;  thus 
completing  the  cycle  of  vegetable  life.  A  preliminary  question, 
however,  presents  itself.  To  understand  how  the  plant  grows  and 
forms  its  various  parts,  we  must  first  ascertain  what  plants  are 
made  of. 


CHAPTER    I. 

OF    THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

Sect.  I.     Of  Organization  in  General. 

10.  The  Elementary  Constitution  of  Plants.  In  considering  the 
materials  of  which  vegetables  are  made,  it  is  not  necessary  at  the 
outset  to  inquire  particularly  into  their  chemical  or  ultimate  com- 
position, that  which  they  have  in  common  with  the  mineral  world. 

2* 


18  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

The  chemistry  of  vegetation  may  be  more  advantageously  treated 
of  hereafter.  As  they  derive  all  the  materials  of  their  fabric  from 
the  earth  and  air,  plants  can  possess  no  simple  element  which 
these  do  not  supply.  They  may  take  in,  to  some  extent,  almost 
every  element  which  is  thus  supplied.  Suffice  it  for  the  present  to 
say,  however,  that,  of  the  about  sixty  simple  substances  now  recog- 
nized by  chemists,  only  four  are  essential  to  vegetation  and  are 
necessary  constituents  of  the  vegetable  structure.  These  are  Car- 
hon.  Hydrogen,  Oxygen,  and  Nitrogen.  Besides  these,  a  few 
earthy  bodies  are  regularly  found  in  plants,  in  small  and  varying 
proportions.  The  most  important  of  them  are  Sulphur  and  Phos- 
phorus, which  are  thought  to  take  an  essential  part  in  the  forma- 
tion of  certain  vegetable  products.  Potassium  and  Sodium,  Calcium 
and  Magnesium,  Silicon  and  Aluminum,  Iron  and  Manganese, 
Chlorine,  Iodine,  and  Bromine.  None  of  these  elements,  how- 
ever, are  of  universal  occurrence,  or  are  actual  components  of  any 
vegetable  tissue  ;  they  occur  either  among  the  materials  which  are 
deposited  on  the  walls  of  the  cells  or  collected  within  them. 

11.  Their  Organic  Constitution.     Although  plants  and  animals 

have  no  peculiar  elements,  though  the  materials  from  which  their 
bodies  spring,  and  to  which  they  return,  are  common  earth  and 
air,  yet  in  them  these  elements  are  wrought  into  something 
widely  different  from  any  form  of  lifeless  mineral  matter.  Un- 
der the  influence  of  the  principle  of  life,  in  connection  with 
which  alone  any  such  phenomena  are  ever  manifested,  the  three 
or  four  simple  constituents  efl^ect  peculiar  combinations,  giving 
rise  to  a  few  organizahle  elements  (27),  as  they  may  be  termed  ; 
because  of  them  the  organized  fabric  of  the  vegetable  or  animal  is 
directly  built  up.  This  fabric  is  in  a  good  degree  similar  in  all 
living  bodies  ;  the  solid  parts  or  tissues  in  all  assuming  the  form  of 
thin  membranes  or  filaments  arranged  so  as  to  surround  cavities, 
or  form  the  walls  of  tubes,  in  which  the  fluids  are  contained.  It  is 
called  organized  structure,  and  the  bodies  so  composed  are  called 
organized  bodies,  because  such  fabric  consists  of  parts  cooperat- 
ing with  each  other  as  instruments  or  organs  adapted  to  certain 
ends,  and  through  which  alone  the  living  principle,  under  whose 
influence  the  structure  itself  was  built  up,  is  manifested  in  the  phe- 
nomena which  the  plant  and  animal  exhibit.  There  is  in  every 
organic  fabric  a  necessary  connection  between  its  conformation 
and  the  actions  it  is  destined  to  perform.     This  is  equally  true  of 


ORGANIZATION.  19 

the  minute  structure,  or  tissues,  themselves,  as  revealed  by  the 
microscope,  and  of  the  larger  organs  which  the  tissues  form  in  all 
plants  and  animals  of  the  higher  grades,  such  as  a  leaf,  a  petal,  or 
a  tendril,  a  hand,  an  eye,  or  a  muscle.  The  term  organization 
formerly  referred  to  the  possession  of  organs  in  this  larger  sense. 
It  is  now  recognized  to  apply  quite  as  well  to  the  intimate  struc- 
ture of  these  larger  parts,  themselves  made  up  of  smaller  organs 
through  which  the  vital  forces  directly  act. 

12.  Distinctions  between  Minerals  and  Organized  Beings.     In  no 

sense  can  mineral  bodies  be  said  to  have  organs,  or  parts  subor- 
dinate to  a  whole,  and  together  making  up  an  individual,  or  an 
organized  structure  in  any  respect  like  that  which  has  just  been 
spoken  of,  and  is  soon  (in  respect  to  plants)  to  be  particularly  de- 
scribed. Without  attempting  to  contrast  mineral  or  unorganized 
with  organized  bodies  in  all  respects,  we  may  briefly  state  that  the 
latter  are  distinguished  from  the  former,  —  1.  By  parentage : 
plants  and  animals  are  always  produced  under  the  influence  of  a 
living  body  similar  to  themselves,  or  to  what  they  will  become,  in 
whose  life  the  offspring  for  a  time  participates  ;  while  in  minerals 
there  is  no  relation  like  that  of  parent  and  offspring,  but  they  are 
formed  directly,  either  by  the  aggregation  of  similar  particles,  or 
by  the  union  of  unlike  elements  combined  by  chemical  affinity,  in- 
dependent of  the  influence,  and  utterly  irrespective  of  the  previous 
existence,  of  a  similar  thing.  2.  By  their  development :  plants 
and  animals  develope  from  a  germ  or  rudiment,  and  run  through 
a  course  of  changes  to  a  state  of  maturity ;  the  mineral  exhibits  no 
phases  in  its  existence  answering  to  the  states  of  germ,  adoles- 
cence, and  maturity,  —  has  no  course  to  run.  3.  By  their  mode 
of  growth :  the  former  increasing  by  processes  through  which  for- 
eign materials  are  taken  in,  made  to  permeate  their  interior,  and 
are  deposited  interstitially  among  the  particles  of  the  previously 
existing  substance  ;  that  is,  they  are  nourished  by  food  ;  while  the 
latter  are  not  nourished,  nor  can  they  properly  be  said  to  grow  in 
any  way  ;  if  they  increase  at  all,  it  is  merely  hy  juxtaposition^  and 
because  fresh  matter  happens  to  be  deposited  on  their  external 
surface.  4.  By  the  power  of  assimilation^  or  the  faculty  that 
plants  and  animals  alone  possess  of  converting  the  proper  foreign 
materials  they  receive  into  their  own  peculiar  substance.  5.  Con- 
nected with  assimilation,  as  a  part  of  the  function  of  nutrition, 
which  can  in  no  sense  be  predicated  of  minerals,  is  the  state  of 


20  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

internal  activity  and  unceasing  change  in  living  bodies;  these 
constantly  undergoing  decomposition  and  recomposition,  particles 
which  have  served  their  turn  being  continually  thrown  out  of  the 
system  as  new  ones  are  brought  in.  This  is  true  both  of  plants 
and  animals,  but  more  fully  of  the  latter.  The  mineral,  on  the 
contrary,  is  in  a  state  of  permanent  internal  repose  :  whatever 
changes  it  undergoes  are  owing  to  the  action  of  some  extraneous 
force,  not  to  any  inherent  power.  This  holds  true  even  in  respect 
to  the  chemical  combinations  which  occur  in  the  mineral  and  in 
the  organic  kingdoms.  In  the  former  they  are  stable  ;  in  the  lat- 
ter they  are  less  so  in  proportion  as  they  are  the  more  under  the 
influence  of  the  vital  principle ;  as  if  in  the  state  of  unstable  equi- 
librium, a  comparatively  slight  force  induces  retrograde  changes, 
through  which  they  tend  to  reassume  the  permanent  mineral  state. 
6.  Consequently  the  duration  of  living  beings  is  limited.  They 
are  developed,  they  reach  maturity,  they  support  themselves  for  a 
time,  and  then  perish  by  death  sooner  or  later.  Mineral  bodies 
have  no  life  to  lose,  and  contain  no  internal  principle  of  destruc- 
tion. Once  formed,  they  exist  until  destroyed  by  some  external 
power  ;  they  lie  passive  under  the  control  of  physical  forces.  As 
they  were  formed  irrespective  of  the  existence  of  a  similar  body, 
and  have  no  self-determining  power  while  they  exist,  so  they  have 
no  power  to  determine  the  production  of  like  bodies  in  turn.  The 
organized  being  perishes,  indeed,  from  inherent  causes ;  but  not 
until  it  has  produced  new  individuals  like  itself,  to  take  its  place. 
The  faculty  of  reproduction  is,  therefore,  an  essential  character- 
istic of  organized  beings. 

13.  Individuals.  The  mass  of  a  mineral  body  has  no  necessary 
limits  ;  a  piece  of  marble,  or  even  a  crystal  of  calcareous  spar, 
may  be  mechanically  divided  into  an  indefinite  number  of  parts, 
each  one  of  which  exhibits  all  the  properties  of  the  mass.  It  is 
only  figuratively  that  we  can  speak  of  a  mineral  individual.  Plants 
and  animals,  on  the  contrary,  exist  only  as  individuals ;  that  is, 
as  beings  composed  of  parts,  together  constituting  aft  independent 
whole,  which  can  be  divided  only  by  mutilation.  Each  may  have 
the  faculty  of  self-division^  or  of  making  offshoots,  which  become 
new  and  complete  individuals.  It  is  in  this  faculty,  indeed,  that 
reproduction  consists.  The  individuality  is  no  less  real  in  those 
animals  of  lower  grades,  and  in  plants,  where  successive  genera- 
tions of  individuals  remain  more  or  less  united  with  the  parent. 


ORGANIZATION.  21 

instead  of  separating  while  the  ofTspring  is  in  the  embryo  or  infan- 
tile state. 

14.  Species.  This  succession  of  individuals,  each  deriving  its 
existence  with  all  its  peculiarities  from  a  similar  antecedent  living 
body,  and  transmitting  it  with  its  peculiarities  essentially  unchanged 
from  generation  to  generation,  gives  the  idea  of  species ;  a  term 
which  essentially  belongs  to  organic  nature,  and  which  is  applica- 
ble only  by  a  figure  of  speech  to  inorganic  things.  By  species  we 
mean  the  type  or  original  of  each  sort  of  plant,  or  animal,  thus  rep- 
resented in  time  by  a  perennial  succession  of  like  individuals :  or, 
if  it  be  preferred,  the  species  is  the  sum  of  such  individuals. 

15.  Life.  All  these  peculiarities  of  organized,  as  contrasted 
with  inorganic  bodies,  will  be  seen  to  depend  upon  this ;  that  the 
former  are  living  beings  or  their  products.  The  great  character- 
istic of  plants  and  animals  is  Zi/e,  which  these  beings  enjoy,  but 
minerals  do  not.  What  is  the  essential  nature  of  the  vitality 
which  so  controls  the  matter  it  becomes  connected  with,  and  what 
is  the  nature  of  the  connection  between  the  living  principle  and  tlie 
organized  structure^  we  are  wholly  ignorant.  We  know  nothing 
of  life  except  by  the  phenomena  it  manifests  in  organized  struc- 
tures. We  have  adverted  only  to  some  of  the  most  universal  of 
these  phenomena,  those  which  are  common  to  every  kind  of  organ- 
ized being.  But  these  are  so  essentially  different  from  the  mani- 
festations of  any  recognized  physical  force,  that  we  are  compelled 
to  attribute  them  to  a  special,  superphysical  principle.  As  we 
rise  in  the  scale  of  organized  structure  through  the  different  grades 
of  the  animal  creation,  the  superadded  vital  manifestations  become 
more  and  more  striking  and  peculiar.  But  the  fundamental  char- 
acteristics of  living  beings,  those  which  all  enjoy  in  common,  and 
which  necessarily  give  rise  to  all  the  peculiarities  above  enumer- 
ated (12),  are  reducible  to  two;  namely,  —  1.  the  power  of  self- 
support^  or  assimilation^  that  of  nourishing  themselves  by  involv- 
ing surrounding  mineral  matter  and  converting  it  into  their  own 
proper  substance ;  by  which  individuals  increase  in  bulk,  or  grow, 
and  maintain  their  life  :  2.  the  power  of  self-division  or  repro- 
duction^ by  which  they  increase  in  numbers  and  perpetuate  the 
species.* 


*  A  single  striking  illustration  may  set  both  points  in  a  strong  light.     The 
larva  of  the  flesh-fly  possesses  such  power  of  assimilation,  that  it  will  increase 


22  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

16.  Difference  between  Vegetables  and  Animals.  The  distinction  be- 
tween vegetables  and  minerals  is  therefore  well  defined.  But 
the  line  of  demarcation  between  plants  and  animals  —  the  two 
kingdoms  of  organized  beings  subject  to  the  same  general  laws  — 
is  by  no  means  so  readily  drawn.  Ordinarily,  there  can  be  no 
difficulty  in  distinguishing  a  vegetable  from  an  animal.  But  the 
questionable  cases  occur  on  the  lower  confines  of  the  two  king- 
doms, which  descend  to  forms  of  the  greatest  possible  simplicity 
of  structure,  and  to  a  minuteness  of  size  that  baffles  observa- 
tion. Even  here  the  uncertainty  is  probably  attributable  rather 
to  the  imperfection  of  our  knowledge,  than  to  any  confusion  of 
the  essential  characteristics  of  the  two  kinds  of  beings.  It  may 
therefore  be  less  difficult  to  define  them,  than  to  apply  the  defini- 
tions to  the  actual  discrimination  of  the  lowest  plants  from  the 
lowest  animals.  The  essential  characteristics  of  vegetables  are 
doubtless  to  be  sought  in  the  position  which  the  vegetable  kingdom 
occupies  between  the  mineral  and  the  animal,  and  in  the  general 
office  it  fulfils.  Plants,  according  to  the  definition  given  at  the 
outset  (1),  are  those  organized  beings  that  live  directly  upon  the 
mineral  kingdom,  that  grow  at  the  immediate  expense  of  the  sur- 
rounding earth  and  air.  They  alone  convert  inorganic,  or  mineral, 
into  organic  matter ;  while  animals  produce  none,  but  draw  their 
whole  sustenance  from  the  organized  matter  which  plants  have 
thus  elaborated.  Plants,  having  the  most  intimate  relations  with 
the  mineral  world,  are  generally  fixed  to  the  earth,  or  other  sub- 
stance upon  which  they  grow,  and  the  mineral  matter  on  which 
they  feed  is  taken  directly  into  their  system  by  absorption  from 
without,  and  assimilated  under  the  influence  of  light  in  organs  ex- 
posed to  the  air ;  while  animals,  endowed  with  volition  and  ca- 
pable of  perceiving  external  impressions,  have  the  power  of  select- 
ing the  food  ready  prepared  for  their  nourishment,  which  is  re- 
ceived into  an  internal  reservoir,  or  stomach.*     The  proper  tissue 

its  own  weight  two  hundred  times  in  twenty-four  hours;  and  such  conse- 
quent power  of  reproduction,  that  Linnaeus,  perhaps,  did  not  exaggerate,  when 
he  affirmed  that  "  three  flesh-flies  would  devour  the  carcass  of  a  horse  as 
quickly  as  would  a  lion." 

*  The  faculty  of  locomotion,  and  even  that  of  "  making  movements  tend- 
ing to  a  determinate  end,"  cannot  be  denied  to  many  plants.  Doubtless  the 
sensibility  to  external  impressions,  which  some  plants  so  strikingly  manifest, 
does  not  amount  to  perception;  yet,  that  the  lowest  animals  possess  conscious- 


CELLULAR    TISSUE.  23 

of  plants,  moreover,  is  composed  of  three  elements  only,  namely, 
Carbon,  Hydrogen,  and  Oxygen.  The  tissue  of  animals  com- 
prises a  fourth  element,  Nitrogen.  Plants,  as  a  necessary  result  of 
assimilating  their  inorganic  food,  decompose  carbonic  acid  and 
restore  its  oxygen  to  the  atmosphere.  Animals  in  respiration  con- 
tinually recompose  carbonic  acid,  at  the  expense  of  the  oxygen  of 
the  atmosphere  and  the  carbon  of  plants.  These  definitions  will 
be  verified,  extended,  and  illustrated  in  the  progress  of  this  vv^ork. 

Sect.  II.     Of  the  Cells  and  Cellular  Tissue  of  Plants  in 

General. 

17.  The  question  recurs.  What  is  the  organized  fabric  or  tissue 
of  plants,  and  how  is  vegetable  growth  effected  ?  The  stem, 
leaves,  and  fruit  appear  to  ordinary  inspection  to  be  formed  of 
smaller  parts,  which  are  themselves  capable  of  division  into  still 
smaller  portions.     Of  what  are  these  composed  ? 

18.  Cellular  Structure.  To  obtain  an  answer  to  this  question,  we 
examine,  by  the  aid  of  a  microscope,  thin  slices  or  sections  of  any 
of  these  parts,  such,  for  example,  as  the  young  rootlet  of  a  seed- 
ling plant.  A  magnified  view  of  such  a  rootlet,  as  in  Fig.  1,  pre- 
sents on  the  cross-section  the  appearance  of  a  network,  the  meshes 
of  which  divide  the  whole  space  into  more  or  less  regular  cavi- 
ties. A  part  of  the  transverse  slice  more  highly  magnified  (Fig.  2) 
shows  this  structure  with  greater  distinctness.  A  perpendicular 
slice  (Fig.  3)  exhibits  somewhat  similar  meshes,  showing  that  the 
cavities  do  not  run  lengthwise  through  the  whole  root  without  in- 
terruption. In  whatever  direction  the  sections  are  made,  the  cav- 
ities are  seen  to  be  equally  circumscribed,  although  the  outlines 
may  vary  in  shape.  Hence,  we  arrive  at  the  conclusion,  that  the 
fabric,  or  tissue,  consists  of  a  multitude  of  separate  cavities,  with 


ness  is  not  certainly  made  out.  But  it  is  becoming  more  and  more  apparent, 
that  the  absolute  distinctions  between  plants  and  animals  are  not  to  be  drawn 
from  this  class  of  characters.  Dr.  Lindley's  definition,  that  "a  plant  is  a  cel- 
lular body,  possessing  vitality,  living  by  absorption  through  its  outer  surface, 
and  secreting  starch"  is  so  far  good  that  it  indirectly  recognizes  the  essential 
function  of  vegetation,  starch  being  one  of  its  organic  products;  yet  it  is  only 
one  special  form  under  which  the  nutritive  matter  created  by  the  plant  occurs, 
and  is  not  so  universal  as  cellulose  itself.  It  is  much  as  if  animals  were  char- 
acterized by  the  faculty  of  secreting  fat. 


24 


THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 


closed  partitions  ;  forming  a  structure  not  unlike  a  honeycomb. 
This  is  also  shown  by  the  fact,  that  the  liquid  contained  in  a  juicy 
fruit,  such  as  a  grape  or  currant,  does  not  escape  when  it  is  cut  in 
two.  The  cavities  being  called  Cells,  the  tissue  thus  constructed 
is  termed  Cellular  Tissue.  When  the  body  is  sufficiently  trans- 
lucent to  be  examined  under  the  microscope  by  transmitted  light, 
this  structure  may  usually  be  discerned  without  making  a  sec- 
tion. We  may  often  look  directly  upon  a  delicate  rootlet  (as  in 
Fig.  1)  or  the  petal  of  a  flower,  or  a  piece  of  a  thin  and  trans- 
parent sea-weed,  and  observe  the  closed  cavities,  entirely  circum- 
scribed by  nearly  transparent  membranous  walls. 


19.  Does  this  cellular  tissue  consist  of  an  originally  homogene- 
ous mass,  filled  in  some  way  with  innumerable  cavities  ?  Or  is  it 
composed  of  an  aggregation  of  little  bladders,  or  sacs,  which,  by 
their  accumulation  and  mutual  cohesion,  make  up  the  root  or  other 
organ  ?  Several  circumstances  prove  that  the  latter  is  the  cor- 
rect view.  1.  The  partition  between  two  adjacent  cells  is  often 
seen  to  be  double  ;  showing  that  each  cavity  is  bounded  by  its 
own  special  walls.  2.  There  are  vacant  spaces  often  to  be  seen 
between  contiguous  cells,  where  the  walls  do  not  entirely  fit  to- 
gether. These  intercellular  spaces  are  sometimes  so  large  and 
numerous,  that  many  of  the  cells  touch  each  other  at  a  few  points 
only ;  as  in  the  lower  stratum  of  the  green  pulp  of  leaves  (Fig.  7). 


FIG.  1.  Por^on  of  a  young  root,  magnified.  2.  A  transverse  slice  of  the  same,  more  mag- 
nified.    3.  A  smaller  vertical  slice,  magnified. 

FIG.  4.  Cellular  tissue  from  the  apple,  as  seen  in  a  section.  5.  Some  of  the  detached  cells 
from  the  ripe  fruit ;  magnified. 

FIG.  6.  Portion  of  a  hair  from  the  filament  of  the  Spider  Lily  (Tradescantla),  magnified ; 
a,  the  cytoblast. 


CELLULAR    TISSUE. 


25 


:qcjC1qQ^E^ 


20Q^S 


3.  When  a  portion  of  any  young  and 
tender  vegetable  tissue,  such  as  an  As- 
paragus shoot,  is  boiled,  the  elementa- 
ry cells  separate,  or  may  readily  be 
separated  by  the  aid  of  fine  needles, 
and  examined  by  the  microscope.  4.  In 
pulpy  fruits,  as  in  the  Apple,  the  walls 
of  the  cells,  which  at  first  cohere  to- 
gether, spontaneously  separate  as  the 
fruit  ripens  (Fig.  4,  5). 

20.  The  vegetable,  then,  is  constructed  of  these  cells  or  vesi- 
cles, much  as  a  wall  is  built  up  of  bricks.  When  the  cells  are 
separate,  or  do  not  impress  each  other,  they  are  generally  round- 
ed or  spherical.  By  mutual  compression  they  become  polyhedral.  . 
As  in  a  mass  of  spheres  each  one  is  touched  by  twelve  others,  if 
equally  impressed  in  every  direction,  the  yielding  cells  become 
twelve-sided  ;  and  in  a  section,  whether  transverse  (as  in  Fig.  2) 
or  longitudinal  (as  in  Fig.  3),  the  meshes  consequently  appear  six- 
sided.  If  the  organ  is  growing  in  one  direction  more  than  another, 
the  cells  commonly  lengthen  more  or  less  in  that  direction,  and 
thus  become  oblong,  cylindrical,  or  tubular  when  nearly  free,  or 
prismatic  when  laterally  impressed.  If  the  force  of  extension, 
compression,  or  nutrition  be  greater  in  one  direction  than  another, 
or  unequal  on  corresponding  sides,  a  corresponding  variety  of 
form  is  produced.  It  is  not  necessary  to  detach  a  cell  in  order 
to  ascertain  its  shape  ;  that  may  usually  be  inferred  from  the  out- 
lines of  their  section  in  two  or  three  directions.  Nor  have  the 
forms  precise  geometrical  regularity ;  they  merely  approach  more 
or  less  closely  the  figures  to  which  they  are  likened. 

21.  The  walls  of  the  cells  are  transparent,  at  least  in  their  early 
state,  and  almost  always  colorless.  In  a  few  cases  the  membrane 
itself  is  said  to  have  a  tinge  of  green,  and  in  the  stems  of  Ferns  it 
is  often  brown.  The  various  colors  which  the  parts  of  the  plant 
present,  the  green  of  the  foliage,  or  the  vivid  hues  of  the  corolla, 


FIG.  7.  A  magnified  section  through  the  thickness  of  a  leaf  of  Illicium  Floridanum,  show- 
ing the  irregular  spaces  or  passages  between  the  cells,  which  are  small  in  the  upper  layer  of 
the  green  pulp,  the  cells  of  which  (placed  vertically)  are  well  compacted,  so  as  to  leave  only 
minute  vacuities  at  their  rounded  ends ;  but  they  are  large  and  copious  in  the  rest  of  the  leaf, 
where  the  cells  are  very  loosely  arranged,  a,  The  epidermis  or  skin  of  the  upper,  b,  of  the 
lower  surface  of  the  leaf,  composed  of  perfectly  combined  thick-walled  cells. 

3 


^  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

do  not  belong  to  the  tissues  themselves,  but  to  the  matters  of  differ- 
ent colors  which  the  cells  contain. 

22.  The  cells  vary  greatly  in  size,  not  only  in  different  plants, 
but  in  different  parts  of  the  same  plant.  The  largest  are  found  in 
aquatics,  and  in  such  plants  as  the  Gourd,  where  some  of  them  are 
as  much  as  one  thirtieth  of  an  inch  in  diameter.  Their  ordinary 
diameter  is  about  the  :j-^^  or  -5^x7  of  an  inch.  In  the  common  Pink, 
it  has  been  computed  that  more  than  5,000  cells  are  contained 
in  the  space  of  half  a  cubic  line,  which  is  equivalent  to  almost 
3,000,000  in  a  cubic  inch. 

23.  Cells  are  sometimes  drawn  out  into  tubes  of  a  considerable 
length,  as  in  hairs,  and  the  fibres  of  cotton,  which  are  long  and 
attenuated  cells.  The  hairs,  or  hair-like  prolongations  from  the 
surface  of  rootlets,  are  good  examples  of  the  kind.  Two  short 
ones  are  seen  in  Fig.  1.  In  Fig.  13,  14,  they  are  more  fully 
illustrated. 

24.  Some  idea  may  be  formed  respecting  the  rate  of  their  pro- 
duction, by  comparing  their  average  size  in  a  given  case  with  the 
known  amount  of  growth.  Upon  a  fine  day  in  the  spring,  many 
stems  shoot  up  at  the  rate  of  three  or  four  inches  in  twenty-four 
hours.  When  the  Agave  or  Century-plant  blooms  in  our  conser- 
vatories, its  flower-stalk  often  grows  at  the  rate  of  a  foot  a  day ;  it 
is  even  said  to  grow  with  twice  that  rapidity  in  the  sultry  climes  to 
which  it  is  indigenous.  In  such  cases,  new  cells  must  be  formed 
at  the  rate  of  several  millions  a  day.  The  rapid  growth  of  Mush- 
rooms has  become  proverbial.  A  gigantic  Puff-ball  has  been 
known  to  grow  from  an  insignificant  size  to  that  of  a  large  gourd 
during  a  single  night ;  when  the  cells  of  which  it  is  entirely  com- 
posed are  computed  to  have  been  developed  at  the  rate  of  three 
or  four  hundred  millions  per  hour.  But  this  rapid  increase  in  size 
is  owing,  in  great  part,  to  the  expansion  of  cells  already  formed. 

25.  Development  of  Cells.  The  whole  potentiality  of  the  plant 
exists  in  the  individual  cells  of  which  it  is  made  up.  In  them  its 
products  are  elaborated,  and  all  the  vital  operations  carried  on. 
Growth  consists  in  their  production,  multiplication,  and  enlarge- 
ment. A  knowledge  of  these  processes  is  therefore  requisite  in 
almost  every  inquiry  that  arises  in  physiological  botany.  Sys- 
tematic botany  and  zoology,  moreover,  as  well  as  anatomy  and 
physiology,  both  animal  and  vegetable,  have  advanced  to  the  point 
at  which  investigations  into  the  development  of  organs  are  of  the 


CELLULAR    TISSUE.  ST 

utmost  consequence.  The  formation,  propagation,  and  growth 
of  cells,  forming,  as  they  do,  the  groundwork  of  anatomy  and 
physiology,  are -subjects  which  for  the  last  few  years  have  tasked 
the  powers  of  the  ablest  investigators.  Such,  however,  are  the  in- 
trinsic difficulties  of  these  investigations,  that  the  subject  is  still 
involved  in  much  obscurity,  especially  in  regard  to  the  formation 
of  cells ;  and  great  differences  of  opinion  prevail  upon  many  other 
essential  points.  At  present,  it  is  hardly  possible  to  separate  what 
is  known  or  reasonably  well  settled  from  what  is  conjectural,  un- 
proved, or  untrue  ;  nor  can  the  more  or  less  conflicting  views  of 
the  most  experienced  observers  be  presented  and  explained  in  such 
an  elementary  treatise  as  this.*  In  respect  to  cellular  develop- 
ment in  plants,  however,  now  that  Schleiden  has  greatly  modified 
his  views,t  the  highest  authorities,  namely,  Mohl,  Schleiden,  and 
Nageli,  have  arrived  at  substantially  similar  conclusions.  These, 
in  their  general  outlines,  may  be  here  presented. 

26.  We  must  distinguish  between  the  original  formation  of  cells 
and  their  multiplication.  We  must  also  distinguish  between  the 
young,  vitally  active  cell,  and  the  completed  cell,  no  longer  capa- 
ble of  multiplication  or  of  having  new  cells  formed  within  it. 

27.  Formation  of  Cells.  Cells  originate  within  other  cells,  or  at 
least  within  living  tissues.  |     They  are  formed   from  organizable 

*  The  best  authorities  for  the  student  to  consult  upon  the  subject  are, — 

1.  The  memoirs  of  Mohl  in  the  Linruna^  the  Botanische  Zeitung^  &c.,  the  most 
important  of  which  are  translated  in  the  Annates  des  Sciences  JVaturelles^  the 
Annals  and  Magazine  of  Natural  History,  and  in  Taylor's  Scientific  Memoirs. 

2.  Those  of  Nageli  in  the  Zeitschrift  filr  Wissensch.  Botanik^  whose  principal 
memoir  has  been  translated  by  Henfrey  for  the  Ray  Society.  3.  Schleiden's 
Principles  of  Scientific  Botany,  translated  into  English  by  Dr.  Lankester.  4. 
Lindley's  Introduction  to  Botany,  4th  edition.  5.  Henfrey's  Outlines  of  Struc- 
tural and  Physiological  Botany  ;  a  compendious  work,  of  which  the  chapters 
on  elementary  structure,  and  all  of  this  author's  writings  upon  the  subject, 
are  especially  excellent. 

t  Grundiize  der  Wissenschaftl.  Botanik,  ed.  3,  reproduced  in  the  Appendix 
to  the  English  translation,  cited  above. 

i  The  Yeast-plant,  developed  in  fermenting  fluids,  if  that  be  a  true  vegeta- 
tion, is  an  exception  to  the  rule.  According  to  Schleiden,  this  is  a  case  of 
"  the  formation  of  cells  without  the  influence  of  another  cell  previously  exist- 
ing." The  material  has  of  course  been  elaborated  in  former  vegetable  cells  ; 
and,according  to  Karsten,  the  ferment-cells,  with  which  the  development 
commences,  already  exist  in  the  juice  of  the  fruit,  and  pass  through  the  filter 
into  the  solution  ;  which  makes  this  a  case  of  cell-multiplication,  rather  than 
of  cell-formation. 


28  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

matter  (II,  vegetable  mucilage,  protoplasm,  &c.)  assimilated  in 
previously  existing  cells,  and  dissolved  in  the  water  which  the  tis- 
sue of  growing  parts  contains.*  This  organizable  material  always 
and  necessarily  consists  of  a  mixture  of  two  classes  of  assimilated 
matter,  one  of  which  is  azotized,  the  other  is  not.  That  is,  one  is 
composed  of  three  elements,  carbon,  hydrogen,  and  oxygen,  and 
exists  in  the  liquid  form  in  the  state  of  vegetable  mucilage,  dex- 
trine, sugar,  &c.,  or  collects  in  a  peculiar  solid  form  in  the  cells, 
as  starch,  or  finally  constitutes  the  proper  and  permanent  wall  of 
the  cell,  under  the  name  of  Cellulose.  The  other  is  composed  of 
nitrogen  in  addition  to  these  three  elements,  and  exists  in  growing 
parts  in  solution,  as  some  state  of  what  is  called  proteine,  and  is 
known  among  vegetable  products  in  the  forms  of  diastase,  albumen, 
gluten,  fibrine,  &c.  The  latter  makes  no  portion  of  the  per- 
manent fabric,  indeed  ;  but  it  plays  an  indispensable  part  in  the 
production  of  cells,  and  always  exists  in  young  and  vitally  active 
cells,  as  a  mucilaginous  lining.  A  weak  solution  of  iodine  causes 
it  to  turn  brown,  and  detaches  it  from  the  proper  wall  of  the  celf. 
According  to  Mohl,  it  appears  earlier  than  the  proper  cell-wall, 
which  is  formed  under  its  influence,  and  is,  as  it  were,  moulded 
upon  it.  Mohl  has  therefore  given  the  appropriate  name  of  ^;ro- 
toplasm  to  this  azotized  mucilaginous  matter. 

28.  From  a  Nucleus  or  Cytollast.  When  new  cells  are  pro- 
duced by  original  formation  within  the  cavity  of  a  parent  cell,  the 
following  processes  appear  to  take  place.  Portions  of  "  the  proto- 
plasm collect  into  a  more  or  less  perfectly  spherical  body,  at  length 
sharply  defined,  the  nucleus  of  the  cell  [cytollast) ;  upon  this  is 
deposited  a  layer  of  protoplasm,  which  expands  as  a  vesicle,  and 
forms  the  subsequent  lining  of  the  cell ;  at  a  very  early  period  the 
whole  becomes  inclosed  by  a  wall  of  cellulose,  and  the  cell  is  com- 
pleted." t  This  plan,  under  a  more  restricted  form,  was  pro- 
pounded, and  until  recently  maintained,  by  Schleiden  as  the  uni- 
versal mode  of  cell-development.  It  is  now  maintained  as  one 
principal   mode   only,  and  in  a  form   essentially   agreeing   with 


*  "  Cells  can  be  formed  only  in  a  fluid  which  contains  sugar,  dextrine,  and 
proteine  compounds." —  Schleiden,  I.  c. 

t  Schleiden^  I.  c,  ed.  3 ;  from  the  Appendix  to  the  English  translation. 
"  This  appears  to  occur  especially  in  the  embryo-sp,c  and  the  embryonal  vesi- 
cle." 


CELLULAR   TISSUE.  29 

Mohl's  view.*  The  gelatinous  nucleus  of  the  cell  often  remains 
adherent  to  some  part  of  the  wall,  where  its  vestiges  frequently 
appear  as  a  dark  spot  after  the  cell  is  full  grown.  Otherwise  it 
lies  free  in  the  cavity,  the  forming  cell-wall  being  disengaged  from 
it  on  every  side  ;  and  sooner  or  later  it  is  dissolved  or  absorbed. 

29.  Without  an  antecedent  Nucleus.  Some  observers  do  not 
admit  that  the  nucleus  plays  an  essential  part  in  cell-formation,  or 
that  it  exists  in  the  first  instance.  Nor  does  it  have  a  place  in 
Schleiden's  account  of  the  formation  of  free  cells  in  fermenting 
fluids,  viz.  :  t  —  "A  globule  of  nitrogenous  substance  originates  ; 
in  this  a  cavity  is  formed,  it  grows,  and  the  complete  cell  has  a 
delicate  coat  of  cellulose,  without  our  being  able  to  determine 
the  epoch  of  its  production."  j: 

30.  Multiplication  of  Cells.  It  is  not  by  original  cell-formation, 
however,  but  by  the  multiplication  of  cells  already  existing,  that 
the  fabric  of  the  vegetable  is  built  up.     A  cell  once  originated,  in 


*  In  Botanische  Zeitung,  Vol.  2,  1844.  The  abstract  of  Mohl's  view  is.  thus 
rendered,  in  the  Appendix,  I.  c.  p.  571,  translated  from  Schleiden's  3d  ed. :  — 
"In  all  vitally  active  cells  a  living  membrane  occurs,  consisting  of  a  nitroge- 
nous layer ;  this  membrane  exists  earlier  than  the  cell-wall  formed  of  cellulose, 
and  therefore  Mohl  calls  it  the  '  primordial  utricle.'  The  new  cells  proba- 
bly originate  by  the  solution  of  the  old  primordial  utricle,  and  the  formation 
of  several  new  ones  effected  through  a  nucleus,  which  always  precedes  the 
cell-formation." 

t  Schleiden,  in  App'x  to  Engl.  TransL,  I.  c.  And  NSgeli,  as  rendered  in  an 
abstract  by  Schleiden,  I.  c.  p.  572.  "  1.  There  is  a  free  cell-formation  without 
a  nucleus  in  certain  of  the  lower  Algae,  and  in  the  formation  of  the  spores  of 
Lichens  and  Fungi.  Sometimes  a  nucleus  is  subsequently  produced  in  the 
completed  cell.  2.  Perfectly  homogeneous  globules  of  mucilage  are  formed, 
the  nucleoli;  around  these  a  perfectly  homogeneous  nucleus,  on  which  a 
proper  membrane  is  soon  to  be  distinguished.  A  homogeneous  layer  of  mu- 
cilage is  deposited  around  the  nucleus;  this  gradually  becomes  thick,  espe- 
cially at  one  side;  then  granular  in  the  interior;  next  it  is  enveloped  by  a 
membrane,  and  the  cell  with  a  parietal  nucleus  is  complete."  On  the  other 
hand,  "  Hoffmeister  holds  that,  in  the  formation  of  a  nucleus,  a  spherical  drop 
of  mucilaginous  fluid  becomes  coated  by  a  membrane,  and  thus  individualized, 
without  the  presence  of  a  corpuscle  of  denser  substance  (a  nucleolus)  inside 
the  spherical  mass  of  mucilage  either  being  essential  or  contributing  to  the 
process."     Henfrey,  Bot.  Gazette.,  1.  p.  128. 

X  There  seems  to  be  little  real  discrepancy  between  this  view  and  those  of 
Grew,  Bauer,  Mirbel,  linger,  and  Endlicher,  which  agree  in  this ;  that  cells 
originate  as  cavities  in  a  mucilaginous  matrix,  and  at  length  acquire  inde- 
pendent walls. 

3* 


30  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

whatever  manner,  has  the  power  of  propagating  itself  by  division 
into  parts,  each  of  which  forms  a  new  cell.  The  modes  by  which 
cells  are  thus  multiplied,  diverse  as  they  appear  to  be  in  the  vari- 
ous processes  of  vegetable  growth,  are  evidently  reducible  to  two  ; 
and  even  these,  if  they  are  now  rightly  understood,  are  only  two 
modifications  of  one  and  the  same  process  of  division^  or  meris- 
matic  multiplication.  Taking  the  most  distinct  cases  for  examples, 
we  may  say  that,  in  the  first  mode, 

31.  The  cell  is  propagated  hj  the  division  of  its  living  contents 
into  two^  four^  or  sometimes  a  greater  number  of  free  new  cells  ; 
the  wall  of  the  original  cell  perishing  or  losing  its  vitality  in  the 
process.  This  can  occur  only  in  cells  whose  walls  have  not  been 
thickened  by  internal  deposition  (39),  and  while  yet  lined  with  the 
vitally  active  layer  of  protoplasm  *  (26,  27).  This  mucilaginous 
lining  becomes  constricted  or  infolded  around  th^  middle,  and  the 
fold  extends  inward  until  it  is  divided,  with  the  whole  contents,  into 
two  parts  (Fig.  64) ;  at  the  same  time,  or  immediately  following 
the  division,  a  wall  of  cellulose  is  deposited  around  each  portion. 
The  two  new  cells  thus  produced  may  at  once  divide  again  in  the 
same  way,  giving  rise  to  four  cells  in  a  parent  cell  (as  in  Fig.  65) ; 
or  the  division  may  be  again  and  again  repeated.  The  delicate 
wall  of  the  parent  cell  is  either  absorbed  or  obliterated  as  the 
new  ones  it  incloses  enlarge,  or  it  remains,  for  a  while  at  least, 
although  no  longer  in  a  living  state.  By  this  method  the  cells 
of  pollen  formed  in  the  anther  of  all  Flowering  plants  (110),  and 

*  This  layer,  according  to  Mohl,  is  a  delicate  and  soft  membrane  of  proto- 
plasm (called  by  him  the  primordial  utricle),  formed  earlier  than  the  cellu- 
lose cell-wall  which  is  soon  deposited  around  it.  Schleiden  has  not  been  able 
to  satisfy  himself  that  this  matter  is  organized  into  a  membrane,  or  that  it  pre- 
cedes the  proper  wall  of  cellulose.  By  terming  it,  without  reference  to  these 
points,  the  mucilaginous  lining,  or  vitally  active  layer  of  protoplasm,  inter- 
posed between  the  proper  wall  of  the  cell  and  its  contents  (nucleus,  gelatinous 
mass,  endochrome,  or  whatever  they  may  be  called),  their  views  are  brought 
into  agreement  with  each  other.  Those  of  Mr.  Thwaites  do  not  essentially 
differ,  except  in  his  pushing  too  far,  as  I  should  suppose,  the  inference,  "  that 
cell-membrane  is  quite  a  subordinate  part  of  living  structure ;  that  its  func- 
tions are  of  a  purely  physical  character;  that  its  principal  office  is  to  protect, 
locate,  or  isolate  the  matter  it  contains,  and  that  any  vitality,  it  possesses  is 
derived  from  the  presence  within  it  of  its  endochrome."  Atn.  ^  Mag.  JVat. 
Hist.,Yo].  18.  —  The  movement  of  the  cilia  on  the  surface  of  the  cell-wall, 
seen  in  so  many  spores,  surely  shows  that  this  possesses  for  a  time  a  vitality 
of  its  own. 


CELLULAR    TISSUE.  31 

the  spores  of  most  Flowerless  plants  (101,  109),  originate.*  It  is 
subservient  to  reproduction,  as  these  examples  show,  rather  than  to 
vegetation.  On  the  one  hand,  it  might  be  ranked  as  a  mode  of 
original  cell-formation ;  on  the  other,  it  passes  by  insensible  grada- 
tions into  the  next  mode,  —  where 

32.  The  cell  is  multiplied  hy  the  formation  of  a  partition  which 
divides  its  cavity  into  two ;  the  original  wall  remaining.  In  this 
way,  a  single  cell  gives  rise  to  a  row  of  connected  cells,  when  the 
division  takes  place  in  one  direction  only,  or  a  plane  or  solid  mass 
of  such  cells,  when  it  takes  place  in  two  or  more  directions ;  thus 
producing  a  tissue.  It  is  in  this  way  that  all  ordinary  vegetating 
or  growing  parts  are  produced  and  increased.  The  division  is 
effected,  as  before,  by  the  annular  constriction  and  infolding  of 
the  mucilaginous  lining  of  the  cell  (the  primordial  utricle  of  Mohl); 
the  circular  fold  meeting  at  the  centre  divides  the  contents  into 
two  portions,  and  a  layer  of  permanent  cell-membrane,  which  is 
somewhat  later  deposited  upon  each  lamella  of  the  fold,  forms  a 
complete  double  partition  ;  thus  converting  one  cell  into  two,  and 
so  on.t 

33.  Although  connected  in  their  origin,  such  cells  may  break 

*  Some  spores  are  produced  by  the  condensation  of  the  whole  contents  of 
the  parent  cell  and  the  acquisition  of  an  investing  cell-membrane,  without  any 
division,  as  in  Conferva  glomerata,  &c.,  or  of  the  undivided  contents  of  one 
end  of  a  cell,  as  in  Vaucheria,  Fig.  71. 

t  This  mode  of  cell-multiplication  was  first  shown  and  most  ably  maintain- 
ed by  Mohl,  as  the  universal  mode  of  increase  in  growing  parts.  It  has  been 
illustrated  from  independent  observations  by  Henfrey,  in  a  paper  read  before 
the  British  Association  at  Cambridge,  in  1846;  and  has  recently  received 
new  confirmation  from  Mitscherlich's  researches  upon  the  development  of 
Conferva  glomerata^  the  plant  upon  which  Mohl's  observations  upon  cell- 
division  were  principally  made.  Henfrey  has  given  an  abstract  of  Mitscher- 
lich's paper  in  Ann.  &/-  Mag.  JVat.  Hist.,  Vol.  1,  new  ser.,  1848,  p.  436.  Schlei- 
den's  statement  of  the  process,  as  rendered  by  his  English  translator  (p.  572), 
is,  —  "  This  fold  of  the  primordial  utricle  is  followed  somewhat  later  by 
a  fold  of  the  cell-membrane  itself,  which,  finally  arriving  at  the  axis  of  the 
cell,  blends,  and  from  the  nature  of  its  origin  forms  a  complete  double  sep- 
tum." But  Mohl,  Henfrey,  and  Mitscherlich  appear  to  agree  that  the  proper 
wall  of  the  parent  cell  is  not  constricted,  only  its  lining  or  primordial  utricle  ; 
and  that  "the  septum  is  certainly  a  new  structure,  a  double  layer  of  membrane 
formed  in  the  fold,"  yet  deposited,  according  to  Mohl  and  Henfrey,  "  gradu- 
ally from  the  circumference  to  the  centre."  "  The  layers  of  the  partition  are 
therefore  continuous  with  the  layers  of  thickening  in  the  interior  of  the  lateral 
walls,"  as  Henfrey  states. 


32 


THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 


apart  at  an  early  period  into  separate  individ- 
uals. In  that  case,  the  result  is  the  same  as 
in  the  preceding  (31) ;  especially  when  the 
cells  are  globular  and  divide  first  in  one  di- 
rection and  next  in  the  opposite  direction  ;  ex- 
cept that  here  the  parent  cell  is,  as  it  were, 
broken  up  into  two  or  four,  each  invested  with 
its  portion  of  the  original  cell-membrane. 
While  in  the  former,  the  old  cell-wall  is  de- 
stroyed or  remains  distinct,  and  the  new  cells 
formed  in  it  acquire  each  its  own  independent 
coating  of  cell-membrane.  This  is  the  more 
apparent  where  the  cell  is  elongated  and  goes 
on  to  form  a  chain  of  cells,  as  in  the  green 
Confervas  of  streams  and  pools.  Fig.  8  rep- 
resents a  portion  of  a  Conferva,  magnified,  so 
as  plainly  to  exhibit  the  formation  of  the  par- 
titions. Here  the  process  of  division  goes  on 
pari  passu  with  that  of 

34.  Gemmation  or  Budding ;  namely,  with  con- 
tinuous growth  from  their  free  extremity,  or 
the  shooting  forth  of  a  protrusion  or  branch 
from  some  part  of  the  surface  of  a  cell,  which  grows  onward  from 
its  apex  in  the  same  way.  A  cell  thus  prolonged  into  a  tube  is 
divided  by  a  transverse  partition ;  the  upper  joint, 
after  elongating  from  its  apex,  has  its  cavity  like- 
wise divided  into  two  by  a  transverse  partition  ;  the 
lowest  of  the^  remaining  stationary,  the  upper 
elongates  and  continues  the  same  process ;  which 
may  thus  go  on  indefinitely.  Fig.  9-12  show 
modifications  of  this  gemmiparous  (or  budding) 
mode  of  growth,  as  seen  in  some  of  the  micro- 
scopic plants  of  doubtful  nature  which  develope  in 
fermenting  infusions. 


FIG.  8.  Branching  summit  of  a  planllet  of  Conferva  glomerala,  magnified ;  after  Mohl ; 
showing,  at  a,  a,  the  partitions  forming  by  the  infolding  process. 

FIG.  9  - 12.  The  minute  infusory  plant  which  developes  in  yeast  and  fluids  which  are  in 
vinous  fermentation,  9.  The  original  vesicle  or  cell,  which  is  forming  a  second  by  a  kind 
of  budding.  10.  The  same,  fanher  advanced.  12.  The  plant  fully  developed  by  the  successive 
production  of  new  ceUs  in  this  manner.  11.  The  same,  or  a  similar  plant,  developing  in  a 
slightly  diflfereni  mode,  nearly  as  in  Fig.  8.    All  the  figures  are  magnified. 


CELLULAR   TISSUE. 


85.  Elongating  and  Ramifying  Cells.  This  onward  growth  may 
take  place,  moreover,  without  the  formation  of  partitions  at  all ; 
when    elongated,   vegetating  cells  *^ 

are  produced,  whether  simple  or 
branched.  The  hair-like  bodies 
that  copiously  appear  on  the  sur- 
face of  young  rootlets  furnish  ex- 
amples of  the  kind,  as  is  shown  in 
Fig.  13,  14.  More  conspicuous 
examples  are  furnished  by  certain 
Alga3  of  the  simplest  structure, 
where  the  cell  grows  out  into  a 
tube  of  uninterrupted  calibre,  or 
branches  as  it  grows  into  a  series 
of  such  tubes  with  the  cavity  per- 
fectly continuous  throughout ;  as 
in  Botrydium  (Fig.  67-70),  where  an  originally  spherical  cell  is 
extended  and  ramified  below  in  the  fashion  of  a  root ;  in  Vauche- 
ria  (Fig.  71),  where  a  slender  tube  forks  or  branches  sparingly; 
and  in  Bryopsis  (Fig.  73),  where  numerous  branches  are  very 

regularly  produced.  In  these 
cases,  the  fully  developed  plant, 
with  all  its  branches,  is  only  one 
proliferous  cell,  extended  from 
various  points  by  this  faculty 
of  continuous  budding  growth. 
The  mycelium  or  spawn  of 
Mushrooms,  and  the  intricate 
threads  of  Moulds  (Fig.  74-76)  are  formed  of  very  attenuated 
branching  cells.  And  in  Lichens,  cells  of  the  same  kind  are 
densely  interwoven  into  a  filamentous  tissue  (Fig.  15). 

36.  Circulation  in  young  Cells.  A  kind  of  circulation  or  move- 
ment of  rotation  has  been  observed  in  numerous  cells,  particularly 
in  those  that  form  the  hairs  of  many  plants,  which  are  well  situated 
for  observation ;  and  it  probably  takes  place  in  most  cells  at  an 
early  period,  while  yet  filled  with  fluid.     The  string  of  bead-like 


FIG.  13.  Magnified  cellular  tissue  from  the  rootlet  of  a  seedling  Maple;  some  of  the  ex- 
ternal cells  growing  out  into  root- hairs.     14.  A  few  of  the  cells  more  highly  magnified. 

FIG.  15.  Ealarigled,  filamentous,  branching  cells  from  the  fibrous  tissue  of  the  Reindeer 
Lichen  (Cladonia  rangiferina),  magnified. 


34  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

cells  which  compose  the  jointed  hairs  of  the  common  Spicier  Lily 
(Tradescantia,  Fig.  6),  show  this  circulation  well,  under  a  magni- 
fying power  of  about  four  hundred  diameters.  With  this  power,  a 
network  of  anastomosing  currents,  rendered  visible  by  the  little 
globules  they  carry  with  them,  will  be  seen  to  move  between  the 
transparent  and  glassy  cell-membrane  and  the  inclosed  colored 
contents,  traversing  the  cell  in  various  directions,  without  much 
regularity,  except  that  the  streamlets  appear  to  radiate  from,  and 
return  to,  the  parietal  cytoblast  (28).  In  this  instance,  it  is  easy 
to  see  that  the  currents  belong  to  the  layer  of  mucilaginous  fluid, 
or  protoplasm,  interposed  between  the  cell-membrane  and  the 
colored  aqueous  contents.  The  same  is  the  case,  according  to 
Mohl's  thorough  observations,  in  the  tubular  cells  of  Chara,  where 
they  may  be  observed  with  an  ordinary  lens ;  and  in  our  Vallisne- 
ria,  where  a  moderate  magnifying  power  shows,  in  the  cells  of  the 
leaves,  a  continuous  rotation  round  the  whole  wall  of  the  cell,  the 
stream  rising  on  one  side  and  descending  on  the  other.  The  cur- 
rent is  powerful  enough  to  carry  along,  not  only  minute  granules, 
but  small  grains  of  chlorophyll  or  green  coloring  matter  (87), 
which  renders  it  abundantly  visible  ;  and  sometimes,  where  the 
green  granular  contents  cohere  in  a  mass  filling  the  centre  of  the 
cell,  it  throws  this  whole  mass  into  slow  revolution  on  its  axis.  In 
these  instances,  the  whole  layer  of  mucilaginous  fluid  takes  part  in 
the  movement.  The  cause  of  this  motion  is  wholly  unknown,  as 
also  the  office  it  subserves.  We  shall  have  occasion  to  refer  to  it 
in  another  chapter,  in  connection  with  other  vegetable  movements. 
At  present,  we  may  merely  remark  that  it  is  not  like  a  true  circu- 
lation, through  vessels,  which  is  characteristic  of  animals. 

37.  Permeability  and  Imbibition.  The  wall  of  the  cells,  at  least  in 
•their  living  or  vitally  active  state,  is  a  perfectly  closed  sac,  desti- 
tute of  openings  or  visible  pores  (although  perforations  sometimes 
appear  in  old  or  effete  cells,  as  in  those  of  Peat-Moss) ;  but,  like 
all  organic  membranes,  it  is  permeable  to  fluids.  The  cell  con- 
stantly contains  a  fluid  thicker  than  water,  and  therefore  tends  to 
imbibe  water  by  endosmosis,*  as  well  as  to  yield  by  exosmosis  *  a 

*  Endosmosis  and  exosmosis  are  names  given  by  Dutrochet  (who  first  illus- 
trated them  in  liquids)  to  a  physical  process  of  permeation  and  interchange 
which  takes  place  in  fluids,  according  to  the  following  law,  briefly  stated. 
When  two  liquids  of  unequal  density  are  separated  by  a  permeable  mem- 
brane, the  lighter  liquid  or  the  weaker  solution  will  flow  into  the  denser  or 


CELLULAR    TISSUE.  35 

portion  of  its  liquid  contents  to  a  contiguous  cell,  which  may  be 
charged  with  contents  of  greater  density  than  its  own.  From  the 
nature  of  the  process  of  assimilation  and  other  operations  carried 
on  in  the  interior  of  cells,  they  must  always  contain  a  denser  fluid 
than  the  water  in  which  aquatic  plants  live,  or  which  is  presented 
to  the  roots  or  other  parts  of  the  surface  of  terrestrial  plants.  This, 
with  the  gaseous  and  other  matters  it  holds  in  solution,  the  vegeta- 
ble must  constantly  tend  to  imbibe  by  endosmosis.  In  virtue  of 
the  same  law,  as  will  hereafter  be  explained,  not  only  is  the  crude 
food  imbibed  by  the  roots,  but  transferred  from  cell  to  cell  to  the 
place  where  assimilation  is  principally  effected  or  growth  is  going 
on.  In  addition  to  this  simpler  process,  animals,  even  of  the 
lowest  grades,  have  a  proper  circulation  through  vessels.  There 
is  no  such  circulation  in  plants. 

38.  Growth  of  Cell-membrane  iiiterstitially.  By  appropriating  the 
assimilated  matter  it  contains  or  imbibes,  the  young  cell  increases 
rapidly  in  size;  its  wall  is  extended  equally  on  every  side  (unless 
something  interferes  with  its  expansion  in  particular  directions),  so 
that  a  larger  space  is  surrounded.     Meanwhile,  instead  of  becom- 


stronger,  with  a  force  proportioned  to  the  difference  in  density  (endosmosis) ; 
but  at  the  same  time,  a  smaller  portion  of  the  denser  liquid  will  flow  out  into 
the  weaker  {exosmosis).  Thus,  if  the  lower  end  of  an  open  tube,  closed  with 
a  thin  membrane,  such  as  a  piece  of  moistened  bladder,  be  introduced  into  a 
vessel  of  pure  water,  and  a  solution  of  sugar  in  water  be  poured  into  the  tube, 
the  water  from  the  vessel  will  shortly  be  found  to  pass  into  the  tube,  so  that 
the  column  of  liquid  it  contains  will  increase  in  height  to  an  extent  propor- 
tionate to  the  strength  of  the  solution.  At  the  same  time,  the  water  in  the 
vessel  will  become  slightly  sweet;  showing  that  a  small  quantity  of  syrup  has 
passed  through  the  pores  of  the  membrane  into  the  water  without,  while  a 
much'larger  portion  of  water  has  entered  the  tube.  The  water  will  continue 
to  enter  the  tube,  and  a  small  portion  of  syrup  to  leave  it,  until  the  solution  is 
reduced  to  the  same  strength  as  the  liquid  without.  If  a  solution  of  gum,  salt, 
or  any  other  substance,  be  employed  instead  of  sugar,  the  same  result  will 
take  place.  If  the  same  solution  be  employed  both  in  the  vessel  and  the  tube, 
no  transference  or  change  will  be  observed.  But  if  either  be  rendered  strong- 
er than  the  other,  a  circulation  will  be  established,  and  the  stronger  solution 
will  increase  in  quantity  until  the  two  attain  the  same  density.  If  two  differ- 
ent solutions  be  employed,  as,  for  instance,  sugar  or  gum  within  the  tube,  and 
potash  or  soda  without,  a  circulation  will  in  like  manner  take  place,  the  pre- 
ponderance being  towards  the  denser  fluid,  and  in  a  degree  exactly  propor- 
tionate to  the  difference  in  density.  Instead  of  animal  membrane,  any  vegeta- 
ble matter  with  fine  pores,  such  as  a  thin  piece  of  wood,  or  even  a  porous 
mineral  substance,  may  be  substituted  with  the  same  result. 


36  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

ing  thinner  as  it  expands,  it  grows  thicker  ;  although  the  increase 
of  surface  at  this  time  is  much  greater  than  that  of  thickness. 
Therefore  it  not  merely  enlarges,  but  grows.  That  is,  it  incorpo- 
rates new  assimilated  matter,  which  penetrates  the  membrane  and 
is  deposited  in  it,  not  as  a  new  layer,  lining  and  strengthening  the 
old,  but  inter stitially ;  so  that  the  enlarging  cell-wall  is  still  as 
homogeneous  and  simple  as  before.  After  attaining,  for  the  most 
part  rapidly,  a  definite  size,  the  cell  ceases  to  enlarge,  and  its  wall 
no  longer  incorporates  new  materials.  Some  cells  remain  in  this 
condition,  with  walls  of  great  tenuity,  as  do  the  parent  cells  in 
which  grains  of  pollen  or  other  new  cells  are  produced  (31) ;  in 
which  case  they  seldom  endure,  but  are  soon  destroyed  or  ab- 
sorbed. The  assimilated  matters  they  contained  were  wholly 
diverted  to  the  new  product  to  which  they  give   rise. 

39.  Thickening  by  Deposition.  In  most  cells  that  make  part  of  a 
permanent  structure,  however,  the  membrane  continues  to  thicken 
after  it  has  ceased,  or  nearly  ceased,  to  enlarge,  no  longer  inter- 
stitially,  but  by  a  deposit  on  its  inner  surface.  The  nature  of  the 
contained  assimilated  matter  is  such,  that,  by  the  mere  abstraction 
of  water,  it  readily  passes  into  a  solid  state  (81).  As  it  organizes 
(doubtless  under  the  influence  of  the  living  lining  of  protoplasm), 
it  solidifies  on  the  surrounding  cell-wall,  which  is  thus  strengthen- 
ed by  a  new  layer  of  cellulose,  or  by  a  succession  of  such  layers. 
Every  degree  of  this  secondary  deposition  occurs,  from  a  slight 
increase  in  the  thickness  of  the  membrane  to  the  filling  up  of  the 
greater  part  of  the  cavity  of  the  cell.  The  older  wood-cells  of  any 
hard  wood  furnish  good  illustrations  of  such  solidification.  Indeed, 
the  difference  between  sap-wood  and  heart-wood  of  trees  is  princi- 
pally owing  to  the  increase  of  this  secondary  deposit,  which  con- 
verts the  former  into  the  latter ;  as  may  be  seen  by  comparing, 
under  the  microscope,  the  tissue  of  the  older  with  that  of  the  newest 
rings  of  wood,  taken  from  the  same  tree.  In  an  ensuing  chapter 
(on  the  internal  structure  of  the  stem),  this  is  shown  in  a  piece  of 
oak  wood.  Fig.  18  represents  a  highly  magnified  cross-section  of 
some  wood-cells  from  the  bark  of  a  Birch,  with  their  calibre  almost 
obliterated  in  this  way.  It  is  by  the  same  process  that  the  tissue 
of  the  stone  of  the  peach,  cherry,  and  other  stone-fruits  acquires  its 
extreme  hardness.  Indurated  cells  of  the  same  kind  are  met  with 
even  in  the  pulp  of  some  fruits,  as  in  the  gritty  grains,  which  every 
one  has  noticed,  scattered  through  the  flesh  of  many  pears,  espe- 


CELLULAR    TISSUE.  37 

cially  of  the  poorer  sorts.  A  section  of  a  few  cells  of  the  kind  is 
represented  in  Fig.  16,  with  their 
cavity  much  reduced  and  rendered 
very  irregular  in  outline  by  such  in- 
crustation. Similar  cells  are  readily 
seen,  with  a  moderate  magnifying 
power,  to  form  a  part  of  the  tissue 
even  of  such  juicy  fruits  as  the  cranberry  and  the  blueberry 
(Fig.  17). 

40.  This  deposited  matter  can  rarely  consist  of  pure  cellulose, 
but  may  include  all  the  various  matters  capable  of  solidification,  of 
whatever  nature,  which  are  introduced  into  the  cells  from  without, 
or  are  elaborated  there.  As,  for  example,  mineral  matters,  small 
quantities  of  which  must  needs  be  dissolved  in  the  water  which 
the  plant  imbibes  by  its  roots,  and  be  deposited  in  the  cells  of 
the  wood  through  which  it  passes,  and  especially  in  those  of  the 
leaves,  where  it  is  concentrated  by  evaporation,  as  will  be  here- 
after illustrated  ;  also,  coloring  matters,  such  as  give  the  different 
tints  to  heart-wood,  and  other  special  solidified  products  formed 
in  the  cells  themselves.  The  cells  fill  up,  therefore,  partly  by  or- 
ganic deposition,  and  partly  by  incrustation. 

41.  Even  when  purified  as  much  as  possible  from  all  admix- 
ture of  foreign  mateT;ials,  the  secondary  deposit  is  found  to  differ 
a  little  from  cellulose,  or  original  cell-membrane,  in  chemical 
composition.  It  contains  a  somewhat  larger  proportion  of  carbon 
and  hydrogen,  and  is  therefore  richer  in  combustible  matter. 
Forming  as  it  does  the  principal  part  of  the  weight  of  wood  {lig- 
nu?n),  it  has  received  the  name  of  Lignine  (also  that  of  Sclera- 
gen) ;  but  it  is  probably  only  cellulose  a  little  modified  or  altered. 
This  difference  in  chemical  composition,  however,  shows  why  the 
hard  woods,  such  as  hickory  and  oak-wood,  which  abound  in  this 
lignified  deposit,  should  be  more  valuable  for  fuel,  weight  for 
weight,  than  the  soft  woods,  which  have  little  of  it  (such  as  bass- 
wood,  &c.) ;  at  least,  when  the  latter  are  not  charged  with  resinous 
matter. 

42.  The  secondary  deposit  often  forms  an  even  and  continuous 
increase  in  the  thickness  of  the  walls  (as  is  shown  in  the  White 
Oak,  in  the  section  on  the  internal  structure  of  the  stem) :  but  it  is 

FIG.  16.  Magnified  section  of  the  gritty  cells  of  the  pear;  the  cavity  almost  filled  with  in- 
crusting  matter.    17.  Similar  cells  from  the  pulp  of  the  blueberry  (Vaccinium  corymbosum). 

4 


THE    ELEMENTARY   STRUCTURE    OF    PLANTS. 


not  unfrequently  distinguishable,  when  highly  magnified,  into  more 
or  less  defined  concentric  layers ;  as  shown  in  Fig.  18,  from  the 

inner  bark  of  the  Birch,  and 
in  Fig.  19,  in  some  cells  of 
proper  wood.  Whether  the 
thickening  deposit  is  distin- 
guishable into  layers  or  not, 
it  is  more  commonly  inter- 
rupted at  certain  points  and 
in  a  definite  way,  so  as  to 
give  the  diminished  cavity 
very  irregular  outlines  ;  as 
we  see  in  Fig.  16  and  Fig. 
17.  This  occurs  in  wood-cells  as  well  as  in  ordinary  rounded 
cells,  and  is  partly  shown  in  Fig.  19.  The  earliest  layers  of  thick- 
ening fail  to  be  deposited  at  certain  points,  consequently  leaving 
thinner  spots ;  the  succeeding  layers  are  exactly  applied  to  the 
next  preceding,  and  leave  precisely  the  same  intervals  :  conse- 
quently, these  unthickened  spots  become  grooves  or  canals  running 
from  the  cavity  of  the  cell  to  the  original  wall,  or  in  that  direction. 
And  it  is  noticeable  that  the  pits  or  canals  of  contiguous  cells  usu- 
ally correspond :  an  obvious  effect  or  use  of  this  adaptation  is  to 
maintain  a  lateral  communication  between  contiguous  cells  of  the 
kind,  notwithstanding  the  thickening  of  their  walls.  No  tissue 
which  we  have  seen  shows  these  lateral  passages  and  their  nature 
more  clearly  than  the  wood  of  the  American  Plane-tree,  or  Button- 
wood  (Fig.  22),  which  at  the  same  time  demonstrates  the  true 
character  of  one  large  class  of  the 

43.  Markings  of  the  walls  of  Cells.  These,  whether  in  the  form  of 
bands,  spiral  lines,  dots,  or  apparent  pores,  all  arise  from  the  un- 
equal distribution  of  the  secondary  deposit.  They  are  portions  of 
the  walls  which  are  either  thinner  or  thicker  than  the  rest.  These 
markings  display  the  greatest  variety  of  forms,  many  of  them  of 
surpassing  elegance.  The  principal  kinds  occur  with  perfect  uni- 
formity in  each  species  or  family,  and  in  definite  parts  of  the 
plant ;  so  that,  in  a  multitude  of  cases,  a  given  species  or  genus 

FIG.  18.  Highly  magnified  croas-section  of  a  bit  of  the  old  liber  of  the  bark  of  the  Birch ; 
the  tubes  nearly  filled  with  a  deposit  of  solid  matter  in  concentric  layers.     (From  Link.) 

FIG.  19.  Highly  magnified  wood-cells  (seen  in  transverse  and  longitudinal  section),  from 
the  root  of  the  Date  Palm ;  showing  the  internal  deposit  in  layers,  and  some  connecting  canals 
or  pits.    (From  Jussieu,  after  Mirbel.) 


CELLULAR    TISSUE. 


39 


m3h 


may  be  as  certainly  identified  by  the  minute  sculpture  of  its  cells 
alone,  as  by  more  conspicuous  external  characters.  They  are 
preserved  even  when  the  tissue  is  fossilized,  and  the  external  form, 
with  every  outward  appearance  of  organization,  is  obliterated. 
Through  thin  slices  and  other  contrivances,  the  hidden  structure 
is  revealed  under  the  microscope,  and  thus  the  true  nature  of  our 
earth's  earliest  vegetation  may  be  often  satisfactorily  made  out.* 
The  simplest  cases  of  these  markings  are  those  of 

44.  Dots  or  Pits,  often 
taken  for  pores ^  such 
as  those  on  the  cells  of 
the  pith  of  Elder  (Fig. 
25),    and    upon   those 
that   are  called  dotted 
ducts;    as  in  Fig.  39, 
and    Fig.  21,    K     All 
markings  of  this  kind 
are  thin  spots,  which, 
for  some  reason,  have 
not  partaken  in  the  gen- 
eral thickening  of  the  wall, 
been  explained  by  supposing  that  a 
slight   enlargement  of  the   original 
wall  takes  place,  which  stretches  the 
nascent  lining,  so  as  to  break  or  fray 
it  into  slits  or  holes  here  and  there. 
But  their  remarkable  regularity,  and 
the  uniformity  with  which  each  suc- 
cessive layer  is  moulded  on  the  pre- 
ceding, with  exactly  corresponding 
interruptions  (42),  forbid  our  adopt* 


*  In  this  way,  and  by  taking  advantage  of  the  fact,  that  the  secondary  de- 
posits in  the  cells  consist  in  part  of  mineral  matter,  which  is  left  behind  in  the 

FIG.  20.  Magnified  cross- section  of  a  small  portion  of  heart- wood  of  the-  Plane-tree  or 
Buttonwood  (Plalanus  occidentalis).  21.  A  corresponding  longitudinal  section,  parallel  with 
the  circumference,  a,  The  dotted  woody  tissue  ;  the  lower  ends  of  the  two  cells  to  which  the 
letters  are  appended  are  divided  lengthwise,  so  as  to  show  the  irregularly  thickened  calibre ;  the 
others  are  mostly  entire,  showing  the  dots:  in  the  cross-section  the  secondary  deposit  is  seen 
to  form  indistinct  layers,  and  some  of  the  dots  to  form  canals  of  lateral  communication,  b,  Dot- 
ted ducts :  the  middle  one  in  the  longitudinal  section  is  obliquely  jointed,     c,  Medullary  ray. 

FIG.  22.  Portion  of  four  cells  of  the  woody  tissue,  with  both  transverse  and  longitudinal 
section,  highly  magnified,  showing  the  canals  or  deep  pits  in  the  thickened  walls,  and  their  ap- 
position in  adjoining  cells:  on  the  cross-section  the  layers  of  deposit  are  more  plainly  visible. 


40 


THE    ELEMENTARY   STRUCTURE    OF    PLANTS. 


iDg  this  mechanical  explanation.  Although  they  are  not  pores  or 
real  perforations  of  the  wall,  as  has  been  thought,  and  perhaps  is 
still  maintained  by  some,  yet  they  often  become  so  with  age,  by 
the  breaking  away  of  the  thin  primarj^  membrane,  after  the  cell 
has  lost  its  vitality.  The  subjoined  dissections  of  the  wood  of  the 
American  Plane-tree,  already  referred  to,  clearly  show  the  true 
nature  of  these  dots,  which  here  abound  on  the  proper  wood-cells 
as  well  as  the  larger  ducts.  Except  in  their  lesser  size  and  great 
er  depth,  arising  from  the  more  extensive  thickening  of  the  tubes 
they  do  not  essentially  differ  from  the  well-known 

45.  Discs,  or  large  circular  dots^  which  mark  nearly  all  the 
wood-cells  of  the  Pine  Family  (Fig.  23,  24).  Uhese  are  thinner 
spaces,  which  consequently  appear  more  transparent  than  the  rest 
of  the  tube  (except  when  filled  with  a  film  of  air),  when  viewed 
by  transmitted  light.  The  discs  of  contiguous  tubes  are  applied  di- 
rectly to  each  other,  face  to  face  (just  as  the 
canals  or  thin  places  of  other  cells  thickened 
by  secondary  deposits  correspond,  42),  and 
each  is  a  little  depressed,  so  that  a  lenticular 
space  is  left  between  them,  as  between  two 
watch-glasses  put  together  by  their  circumfer- 
ences. They  are  seldom  found  on  the  sides 
of  the  wood-cells  that  look  towards  the  bark 
or  towards  the  pith  ;  while  they  abound  in  a 
section  made  in  the  direction  of  the  lines  of 
silver-grain.  The  dots  on  the  wood-cells  of 
the  Plane-tree,  on  the  contrary,  are  most  abundant  on  the  sides 
that  look  towards  the  centre  and  the  circumference  of  the  trunk. 
Although  of  universal  occurrence  in  the  Pine  Family  and  the  relat- 
ed order  Cycadacese,  these  discs  are  not  restricted  to  them,  as  was 
once  supposed.  Mr.  Brown  long  since  showed  that  the  wood  of 
the  Winter's-bark  tree  was  similarly  marked ;  and  our  Fig.  33 
represents  them  as  they  appear  in  the  Star- Anise  of  Florida,  which 
belongs  to  the  same  natural  group  of  plants.     They  are  said  to  be 


(\ 


\j 


ashes,  Prof.  Bailey,  of  West  Point,  has  enabled  us  to  detect  and  distinguish 
vegetable  tissues  in  anthracite  coal.  See  SillimarCs  Journal,  Vol.  I.,  New 
Series. 


FIG.  2.3.    Piece  of  a  Pine-shaving,  magnified,  to  show  the  dots  or  discs  which  appear  on  the 
cells  of  aU  Ckjniferous  wood.    24.  A  separate  ceU  of  the  above,  more  strongly  magnified. 


CELLULAR   TISSUE. 


41 


"  common  in  aromatic  trees  "  ;  probably  under  forms  scarcely  if 
at  all  distinct  from  ordinary  dotted  wood-cells. 

46.  Bands,  Rings,  or  Spiral  Markings.  These  are,  in  most  cases  at 
least,  definite  portions  of  the  wall  more  thickened  than  the  rest ; 
as  is  shown  by  the  spiral  vessel,  where  the  secondary  formation  is 
restricted  to  a  delicate  thread,  capable  of  being  unwound  (60) ; 
and  particularly  by  the  thick  plate  which  winds  around  in  the  cells 
of  certain  Cacti,  like  a  spiral  staircase  (Fig.  29).  Markings  of  this 
kind  (which  are  rarely  thick  and  projecting  as  in  the  last  exam- 
ple) occur  as  rings  (Fig.  43),  or  fragments  of  rings  (Fig.  44),  but 
more  frequently  as  spiral  threads  or  bands  (Fig.  26),  sometimes  as 
branching  threads  (Fig.  27);  all  of  which,  however,  exhibit  a  spiral 
tendency.  The  elongated  cells  which  form  the  hairs  on  the  seeds 
of  many  Acanthaceous  plants  exhibit  these  markings  in  great  va- 
riety. Two  such  cells  from  the  same  seed,  one  with  a  series  of 
rings,  the  other  with  a  continuous  spiral  thread,  are  represented 
in  Fig.  31.  Sometimes  a  band  of  fibres  appears  to  ascend  in 
the  same  direction  :  occasionally  two  spiral  threads  seem  to 
wind  in  opposite  directions ;  and  sometimes  branching  threads  in- 
osculate and  form  a  kind  of  network  on  the  membrane,  as  in  Fig. 


28.     Often  the  rings  or  turns  of  the  spiral  thread  are  nearly  in 
contact  (Fig.  45) ;  while  as  frequently  they  are  separated  more  or 


FIG.  25,    Cell  of  the  pith  of  Elder,  marked  with  oblong  dots. 

FIG.  26.    Cells  of  the  leaf  of  Sphagnum,  or  Peat  Moss,  marked  with  a  spiral  frbrp. 

FIG.  27-30.    Spirally  banded  cells  from  species  of  Cactus,  after  Schleiden. 

FIG.  31.  Hairs  from  the  seed-coat  of  Ruellia  strepens  ;  one  with  a  spiral  band,  the  other 
with  a  set  of  rings  developed  on  the  inner  surface  of  the  tube. 

FIG.  32.  Tissue  from  the  lining  of  the  anther  of  Cobaea  scandens  ;  where,  the  delicate  walla 
of  the  cells  being  soon  obliterated,  the  fibrous  bands  with  which  they  were  marked  remain. 


43  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

less ;  as  if  the  cell-membrane  had  extended  after  the  thread  was 
deposited,  which  is  probably  the  case. 

47.  The  delicate  walls  of  some  such  cells  are  torn  or  obliterated 
at  maturity,  while  the  firmer  bands  or  fibrous  markings  remain  in 
the  form  of  separate  threads ;  as  in  the  tissue  that  lines  the  walls 
of  the  anther  (Fig.  32).  In  a  similar  manner  the  spirally-marked 
tubes  that  are  mingled  with  the  seeds  of  the  Hepatic  Mosses  are 
converted  into  elastic  spiral  threads  (Fig.  85).  So,  also,  the  del- 
icate cells  or  hairs  that  invest  the  coat  of  some  seeds,  which  con- 
tain a  spirally -coiled  thread,  give  way  when  moistened,  or  are 
torn  asunder  by  the  force  with  which  the  thread  uncoils. 

48.  Free  Gelatinous  Coils  in  Cells.  In  many  cases,  however,  the 
spiral  deposit  in  the  cells  which  form  the  hairs  on  the  surface  of 
seeds,  and  of  some  seed-like  fruits,  remains  of  a  gelatinous  con- 
sistence, and  lies  loose  in  the  cell.  When  moistened,  water  is 
absorbed  by  endosmosis,  the  gelatinous  contents  swell,  burst  the 
cell-membrane  (at  the  same  time  frequently  forcing  it  away  from 
its  attachment),  and  gush  out  in  the  form  of  uncoiling  mucilagi- 
nous threads.  Examples  of  the  kind  are  furnished  by  the  seeds  of 
Collomia  and  Gilia ;  and  very  striking  ones  by  hairs  or  papillae  on 
the  seed-like  fruits  of  numerous  species  of  Senecio  and  the  allied 
genera.  Those  of  Crocidium  project  a  thick  mucilaginous  twisted 
band,  in  place  of  a  thread.  This  structure  is  known  to  be  com- 
mon on  the  surface  of  seeds  and  seed-like  fruits ;  one  purpose 
which  it  subserves  will  be  pointed  out  in  a  future  chapter. 

49.  Of  the  same  nature  as  the  last,  probably,  as  maintained  by 
Nageli  and  Schleiden,  are  the  loose  bodies,  thickened  at  one  end 
and  tapering  to  a  point  at  the  other,  which  are  found  in  the  anthe- 
ridia  of  Mosses  and  Liverworts,  in  the  young  leaves  of  Ferns,  &c. ; 
and  which,  on  account  of  their  exhibiting  an  active  vermicular  mo- 
tion when  first  extricated  from  the  cell  in  water,  were  denominat- 
ed Phytozoa  by  Grisebach. 


Sect.  III.     Of  the  Kinds  or  Transformations  of  Cellular 
Tissue  ;  viz.  Woody  Tissue,  Ducts,  etc 

50.  The  statements  of  the  preceding  section  apply  in  general  to 
the  cells  of  which  all  plants  are  composed,  irrespective  of  the 
manifold  forms  they  may  assume,  and  of  some  peculiar  transfor- 
mations they  may  undergo.     Some  of  these  should  now  be  speci- 


PARENCHYMA.  43 

fied,  as  they  give  rise  to  kinds  of  tissue  so  unlike  the  ordinary- 
cellular,  in  outward  appearance  at  least,  that  they  have  always 
been  distinguished  by  special  names.  We  allude  particularly  to 
what  is  called  Woody  Tissue  or  Woody  Fibre,  and  Vascular  Tissue 
or  Vessels,  of  various  forms.  Even  since  the  nature  of  the  vege- 
table structure  has  been  in  a  good  degree  rightly  apprehended, 
these  have  been  considered  as  essentially  different  kinds  of  tissue, 
of  independent  origin.  But  we  now  know  that  they  are  modifica- 
tions of  one  common  type,  the  cell,  and  are  produced  in  the  same 
mode  as  ordinary  cells ;  so  all  the  statements  of  the  foregoing  sec- 
tion, in  respect  to  the  formation,  multiplication,  and  growth  of  cells, 
are  equally  applicable  to  these  also.  Some  kinds  differ  from  or- 
dinary cells  in  shape  alone ;  others  result  from  their  combination 
or  confluence.  This  is  shown  in  two  ways :  first,  by  noting  the 
intermediate  gradations  which  may  be  found  between  every  par- 
ticular sort ;  and  second,  by  watching  their  development  and  tra- 
cing them  directly  from  their  earliest  condition,  as  ordinary  cells, 
to  the  peculiar  forms  they  soon  assume.  The  first  of  the  kinds 
enumerated  below  is  typical  cellular  tissue  ;  the  second,  through  a 
slight  change  in  the  development,  introduces  the  special  forms. 

51.  Pareiichyma  is  the  substantive  name  applied  to  ordinary 
membranous  cellular  tissue  in  general,  such  as  that  which  forms 
the  pith  of  stems,  the  outer  bark,  &c.  In  the  most  restricted  ap- 
plication, it  belongs  to  such  tissue  when  composed  of  angular  or 
polyhedral  cells  (as  in  Fig.  1-3,  13,  &c.)  ;  the  distinctive  name 
of  Merenchyma  hsLving  been  proposed  for  the  looser  tissues  (as  in 
Fig.  7,  and  in  the  pulp  of  leaves  and  fruits  generally),  formed  of 
rounded  or  ellipsoidal  cells,  that  is,  where  they  do  not  mutually 
impress  each  other  into  plane  faces.  But  this  distinction  vanishes 
in  the  numberless  intermediate  states;  and  the  name  of  Paren- 
chyma is  applied  to  both.  That  in  which  the  walls  barely 
touch  each  other,  more  or  less  extensively,  and  leave  intervening 
spaces  where  the  ends  or  sides  are  rounded  off,  is  termed  by 
Schleiden  incomplete  parenchyma.  The  principal  forms  of  com- 
plete parenchyma,  where  the  cells  are  in  perfect  contact  on  every 
side,  and  the  sections  are  consequently  several-sided,  are  designat- 
ed by  adjective  terms ;  as  the  regular,  when  the  cells  are  dodeca- 
hedral  or  cubical ;  the  elongated  or  prismatic,  when  extended  lon- 
gitudinally ;  and  the  tabular,  when  cubical  cells  are  much  flatten- 
ed ;  one  kind  of  which,  called  the  muriform,  because  the  laterally 


44  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

compressed  cells  appear  in  the  magnified  section  like  courses  of 
bricks  in  a  wall,  is  seen  in  the  silver-grain  of  wood  (Fig.  20,  c). 

52.  ProsenchjTna  is  the  general  name  to  designate  tissues  formed 
of  elongated  cells,  with  pointed  or  conical  extremities ;  their  nar- 
rowed ends  overlapping  and  thus  filling  up  the  intervening  spaces 
which  must  otherwise  exist.  Every  gradation  may  be  traced  be- 
tween this  and  incomplete  parenchyma.  As  to  length,  such  cells 
vary  from  fusiform,  or  spindle-shaped,  only  three  or  four  times 
longer  than  broad,  to  tuhular,  and  to  tubes  so  long  and  narrow  that 
they  are  commonly  called  fibres.  As  to  their  extremities,  they 
are  often  sp  blunt,  and  applied  to  each  other  with  such  moderate 
obliquity,  that  they  are  more  properly  said  to  be  placed  end  to  end 
than  side  by  side  ;  while,  again,  precisely  similar  cells,  sometimes 
even  in  the  same  bundle,  exhibit  flattened  ends  resting  directly  one 
over  the  other.*  Nor  can  we  draw  any  fixed  line  of  distinction 
from  the  thickness  of  the  walls.  Indeed,  no  one  can  spend  a  few 
hours  over  the  microscope  in  diligently  examining  the  tissues  of 
two  or  three  of  the  commonest  plants,  without  perceiving  that 
there  is  no  essential  difference  between  cellular  and 

53.  Woody  Tissue,  (P/eMre;wc^?/ma  of  Meyer  and  Lindley.  Woody 
Fibre  of  the  older  authors).  Wood,  which  makes  up  so  large  a 
part  of  trees  and  shrubs,  and  a  distinguishable  portion  in  all  Phoe- 
nogamous  (110)  herbaceous  plants,  is  wanting  in  Mosses  and  plants 
of  still  lower  grades,  such  as  Lichens,  Sea-weeds,  and  Fungi. 
That  is,  in  the  latter  there  is  no  formation  corresponding  to  the 
wood  of  higher  plants,  although  many  of  them  exhibit,  at  least  in 
certain  parts,  prosenchymatous  cells,  and  others  drawn  out  into 
tubes  or  hollow  fibres  of  greater  length  and  tenuity  than  are  those 
of  ordinary  wood  ;  such,  for  instance,  as  the  interlaced  fibrous  tis- 
sue of  Lichens  (Fig.  15).  Nor,  on  the  other  hand,  does  the  proper 
woody  system  of  trees  (except  in  the  Pine  Family)  consist  entirely 
of  that  form  which  has  received  the  special  name  of  woody  tissue, 
but  three  or  four  other  sorts  are  variously  intermingled  with  it. 
Indeed,  there  are  some  trees  whose  wood  is  almost  entirely  com- 
posed of  true  parenchemytous,  or  of  large  dotted  (58)  cells  ;  while 
in  stone-fruits,  and  many  like  cases,  common   parenchemytous 

The  forming  woody  tissue,  as  seen  in  a  germinating  plant  or  young  root- 
let, consists  of  prismatic  cells,  with  square  ends  ;  as  these  lengthen,  their  ends 
push  by  each  other,  and  so  become  oblique  and  wedged  together,  or  converted 
into  prosenchyma. 


WOODY   TISSUE.  45 

cells  acquire  by  incrustation  a  ligneous  consistence  and  even 
greater  density  than  wood  (39).  Nevertheless,  the  principal 
and  characteristic  component  of  wood  in  general  is  thick-walled 
prosenchyma.  So  that  this  takes  the  name  of  woody  tissue  even 
in  the  bark,  leaves,  &c.  Fig.  21  represents  some  pleurenchyma 
along  with  the  other  usual  elements  of  the  wood,  and  shows  the 
manner  in  which  these  woody  tubes  are  spliced  together,  as  it 
were,  by  their  overlapping  pointed  ends.  Their  diameter,  in  this 
instance,  is  about  the  ^xhttt  o^  ^^  inch.  Those  of  our  Linden  or 
Bass-wood  (a  few  of  which  are  shown  in  Fig.  36,  37)  are  rather 
larger,  but  not  more  than  xViJir  ^^  ^^  i"^^  ^"  diameter.*  Their 
size  varies  in  different  plants  almost  as  much  as  ordinary  cells 
do,  but  they  are  usually  much  smaller  than  parenchyma,  espe- 
cially in  herbaceous  plants.  Perhaps  the  largest  are  found  in 
the  Pine  Family,  where  they  are  of  a  peculiar  sort,  and  are  often 
as  much  as  ^^^  or  ^^jj  of  an  inch  in  diameter.  The  density  or 
closeness  of  grain  in  wood,  however,  does  not  depend  so  much 
on  the  fineness  of  the  wood-cells  as  upon  the  intermixture  of  other 
kinds  of  tissue,  and  the  thickness  of  their  walls.  This  is  much 
greater  in  proportion  to  their  diameter  than  in  ordinary  parenchy- 
ma, and,  with  their  slenderness  and  their  very  compact  arrange- 
ment into  threads  or  masses  which  run  lengthwise  through  the 
stem,  conspires  to  give  the  toughness  and  strength  which  charac- 
terize those  parts  in  which  this  tissue  abounds.  A  transverse  sec- 
tion under  the  microscope  shows  that  woody  tissue  is  composed 
of  lengthened  cells,  that  is,  of  hollow  tubes  and  not  of  solid  fibres 
(Fig.  20,  36,  (fee).  But  as  their  walls  thicken  by  the  secondary 
or  incrusting  deposit  to  which  they  are  especially  liable  (39  -41), 
the  calibre  diminishes,  and  in  old  wood  sometimes  becomes  nearly 
obliterated.  This  thickening  usually  occurs  evenly  in  woody  tis- 
sue ;  at  least,  bands  or  spiral  lines  are  seldom  seen  in  it ;  but 
small  dots  or  pores,  the  nature  of  which  has  already  been  explain- 
ed (44),  are  not  uncommon.  They  are  well  shown  in  the  wood 
of  the  Plane-tree  (Fig.  20-22).  Of  similar  character,  only  more 
conspicuously  marked,  is  the 

54.  Disc-bearing  Woody  Tissue  (Glandular  Woody   Tissue  of 
Lindley),  which  forms  the  wood  in  the  Pine  Family.     The  nature 


*  Lindley  states  that  the  woody  tubes  of  the   Linden  are  as  much  as  the 
155  of  an  inch  in  diameter;  but  I  find  none  of  any  thing  like  this  size. 


46 


THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 


of  the  discs,  or  thin  spots,  has  just  been  explained  (45).  On  ac- 
count of  their  markings  and  unusually  large  size,  and  because  in 
the  Pine  Family  they  make  up  the  wood  without  any  admixture 

of  ducts,  these  peculiar  wood-celfs 
have  been  thought  to  be  rather  a 
form  of  vascular  tissue.  But  in  the 
Star-Anise  the  same  kind  of  mark- 
ings is  found  on  undoubtedly  genu- 
ine woody  tissue  (Fig.  33).  In  the 
Yew,  on  the  other  hand,  where  the 
discs  are  few,  delicate  spiral  mark- 
ings appear  (Fig.  34),  showing  a 
'M°\\  iySfe^    perfect  transition  between  the  prop- 

er woody  and  the  vascular  tissues; 
as  is  seen  by  comparing  the  figure 
with  that  of  a  spirally  marked  duct 
of  Bass-wood,  Fig.  36,  a. 
55.  Bast  Tissue,  or  Woody  Tissue  of  the  Liber.  The  hast  or 
iass,  fibrous  inner  bark,  or  liher,  as  it  is  variously  termed,  of  those 
plants  that  have  a  true  bark  separable  from  the  wood  of  the  stem, 
is  principally  pleurenchyma,  consisting  of  much  longer,  very 
thick-sided,  and  usually  tougher,  but  more  soft  and  flexible  cells, 
than  those  of  the  wood  itself.  These  properties  are  "  probably 
given  them  that  they  may  possess  the  strength,  combined  with  flex- 
ibility, which  their  position  near  the  circumference  of  a  branch 
renders  necessary."  These  especially  adapt  them  to  the  useful 
purposes  they  so  largely  subserve  for  clothing  and  cordage. 
The  textile  fibres  of  flax,  hemp,  &c.,  are  all  derived  from  this 
woody  tissue  of  the  bark,  separated  from  the  brittle  cells  of  the 
wood  itself,  and  freed  from  the  surrounding  thin-sided  parenchy- 
ma by  maceration  (which  soon  decomposes  the  latter)  and  me- 
chanical means.  Cotton  differs  from  linen  in  many  respects  ;  it 
consisting  of  hairs,  or  long  tubular  cells,  growing  on  the  seeds, 
with  very  thin  walls,  which  collapse  so  that  they  twist  variously, 
which  gives  them  a  peculiar  adaptation  to  be  spun,  or  drawn  out 
together  by  torsion  into  a  thread.     But  the  walls  have  none  of  the 

FIG.  33.  Magnified  woody  tissue  of  Illicium  Floridanum  (longitudinal  view),  marked  with 
large  dots,  like  the  discs  on  the  wood-cells  of  the  Pine  Family. 

FIG.  34.  Magnified  woody  tissue  from  the  American  Yew  (longitudinal  view),  showing 
delicate  spiral  markings ;  some  of  the  cells  also  showing  the  disc-like  markings  or  dots  of  ordi- 
nary Coniferae.    Across  the  base  is  seen  a  portion  of  a  medullary  ray. 


"WOODY    TISSUE. 


47 


thickness  and  toughness  which  characterize  the  liber-cells.  Fig. 
35  represents  one  of  the  bast-cells  of  our  Bass-wood  35  35 
or  Linden,  with  a  portion  of  another ;  while  Fig.  36, 
37,  represent  a  few  of  the  cells  of  the  wood  from 
the  same  stem,  and  equally  magnified  ;  showing  the 
great  difference  in  the  length  of  the  fibre-shaped 
cells.  Being  a  soft  wood,  the  cells  of  the  latter  have 
thin  walls,  as  is  seen  on  the  cross-section  of  two  of 
them  at  the  top  ;  while  the  section  of  one  of  the 
bast-cells  shows  a  thick  wall  and  very  small  cali- 
bre. The  disproportion  in  length  is  still  greater  in 
our  Leather- wood,  which  has  a  bark  of  extraordi- 
nary toughness,  «sed  for  thongs,  while  the  wood 
itself  is  very  brittle  and  tender.  Its  capillary  bast- 
cells  measure  from  an  eighth  to  a  sixth  of  an  inch 
in  length,  with  an  average  diameter  of  ^-uW  of  an 
inch  (so  that,  if  the  whole  length  of  a  cell,  magnified 
as  in  Fig.  38,  were  given,  the  figure  would  be  from 
a  foot  to  nearly  a  foot  and  a  half  in  length),  while 
those  of  the  wood  itself  are  only  the  y^^  of  an  inch 
long.  Among  the  bast-cells  are  found  the  longest 
cells  which  occur  in  any  tissue.  Schleiden  says  that 
he  has  measured  those  which  were  four  or  five 
inches  long.     They  are  of  great  length  in  the  Milk-  ^^ 

weed  Family,  and  in  the  Dogbane,  or  Indian  Hemp, 
the  tough  bark  of  which  accordingly  furnishes  the  ab- 
origines a  sort  of  ready-made  cordage.  In  these  fam- 
ilies they  are  said  by  Schleiden  frequently  to  exhibit 
"  very  delicate  spiral  fibres,  crossing  each  other.  In 
some  spots  their  cavity  becomes  entirely  obliterated  ; 
whilst  in  others  they  are  swollen  and  vesicular,  and 
contain  a  true  milky  juice."  So  that  they  are  the 
milk-vessels  in  these  plants ;  at  least  in  part.  The 
ribs,  with  the  veins  and  veinlets,  that  form  the  fibrous 
^^  framework   of  leaves,  giving  to  them   the    requisite 

firmness,  are  chiefly  of  the  same  kind  of  woody  tissue  as  those  of 
the  bark. 


\!\ 


FIG.  35.    Two  bast-cells  from  the  bark  of  the  American  Bass-wood,  magnified. 

FIG,  36.  Some  woody  tissue  from  the  wood  of  the  same  :  a,  upper  end  of  a  spirally-marked 
duct.     37.  A  separate  cell  from  the  wood.    All  magnified  to  the  same  degree  as  Fig.  35, 

FIG.  38.  Ends  of  some  bast  cells  from  the  bark  of  the  Leather- wood  (Dirca  palustris),  highly 
magnified. 


48 


THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 


56.  The  woody  tissue  runs  lengthwise  through  the  stem,  root,  or 
other  organ  (except  in  reticulated  leaves,  and  there  its  ramifica- 
tions all  spread  in  one  plane)  ;  for  this  reason,  it  is  sometimes  des- 
ignated as  Longitudinal  Tissue^  the  Vertical  or  Longitudinal  Sys- 
tem of  the  stem,  &c.  It  shares  this  name,  however,  with  some 
other  forms  of  tissue  which  accompany  it,  particularly  in  the  wood. 
These  all  agree  in  exhibiting  markings  of  some  kind  on  their 
walls,  and  in  being  larger  than  woody  tissue  :  they  are  all  more  or 
less  tubular,  or  conspire  to  form  tubes  of  considerable  length,  and 
hence  they  have  all  been  combined,  in  a  general  way,  under  the 
name  of 

57.  Vascular  Tissue  or  Vessels.  This  is  an  unfortunate  name,  how- 
ever, and  apt  to  mislead,  like  most  of  those  in  botany  that  are 
based  on  loose  analogies  with  the  animal  kingdom.  To  avoid  or 
correct  the  erroneous  impressions  that  are  so  prevalent,  it  should 
be  remembered  that  these  so-called  vessels  are  comparatively  un- 
essential modifications  of  cellular  tissue,  and  are  wholly  unlike  the 
veins  and  arteries  of  animals.  It  is  much  better  to  call  them  ducis^ 
a  name  appropriate  to  their  nature  and  office,  and  leading  to  no 
false  inferences.  Their  true  nature  is  most  readily  shown  in  the 
largest  and  most  conspicuous  form,  which  often  exhibits  unequivo- 
cal indications  of  its  cellular  origin,  namely, 

58.  Dotted  Ducts,  called  also  Pitted  or  Vasiform  Tissue,  Bothren- 
chyma,  &c.  (Fig.  38,  39).  They  have  likewise  been  termed  Po- 
rous Cells  or  Porous  Vessels ;  but  the  round  or 
oblong  dots  that  characterize  them  are  thin 
places  where  the  wall  has  not  been  thickened 
by  an  internal  incrusting  deposit,  as  has  al- 
ready been  explained  (44),  and  not  perfora- 
tions, except  in  old  cells  where  the  primary 
membrane  is  obliterated  at  these  points.  Some- 
times they  are  continuous  tubes  of  considerable 
length  (Fig.  40) ;  but  commonly,  the  circular 
lines  which  they  exhibit  at  short  intervals  (as  in 
Fig.  39),  and  the  imperfect  transverse  partition 

which  is  often  found  at  these  points,  plainly  indicate  their  compo- 
sition ;  showing  that  they  are  made  up  of  a  row  of  cells,  with  the 
intervening  partitions  more  or  less  obliterated.     In  Fig.  21,  some 

FIG.  39.    Portion  of  a  dotted  duct  from  the  Vine,  evidently  made  up  of  a  series  of  short  cells. 
FIG.  40.    Part  of  a  smaller  dotted  duct,  showing  no  appearance  of  such  composition. 


VASCULAR    TISSUE. 


49 


of  these  ducts,  shown  in  place  among  the  woody  tissue,  are  seen 
to  have  oblique  partitions  of  the  same  kind.  An  examination  in 
the  forming  state  confirms  this  view  ;  and  in  the  young  stems  of 
herbaceous  plants,  they  may  often  be  separated  artificially  into 
their  primitive  elements.  These  jointed  ducts  are  occasionally 
branched,  giving  further  proof  that  they  are  aggregations  of  con- 
fluent cells.  Dotted  ducts  are  usually  met  with  in  the  wood  alone, 
where  they  commonly  abound.  Being  of  greater  calibre  than  any 
other  cells  or  vessels  found  there,  they  form  the  pores  so  conspic- 
uous to  the  naked  eye  on  the  cross-section  of  many  kinds  of  wood, 
such  as  of  Oak,  Chestnut,  and  Mahogany,  as  well  as  the  lines  or 
channels  seen  on  the  longitudinal  section.  Their  size,  compared 
with  that  of  the  wood-cells  in  the  wood  of  the  Plane-tree,  is  shown, 
both  in  longitudinal  and  transverse  section,  in  Fig.  20,  21. 

59.  Reticulated,  Banded,  and  Scalariform  Ducts  are  the  modifications 

of  what  is  more  strictly  called  vascular  tissue  ( Trachenchyma  of 
Morren  and  Lindley)  which  most  resemble  dotted  ducts ;  and 
which-  usually  take  their  place,  or  occur  with  them,  in  the  stems 
of  herbaceous  and  small  woody  plants.  There  is  no  important 
diflference  between  them  :    indeed,  they  are  often  distinguishable. 


a  por- 


FIG.  41.    Scalariform  ducts  of  a  Fern,  rendered  prismatic  by  mutual  pressure. 

FIG.  42.    Similar  duct  of  a  Fern,  torn  into  a  spiral  band. 

FIG.  43.    Duct  from  the  Wild  Balsam  or  Jewel- weed;  the  coils  of  the  thread  distant ; 
lion  forming  separate  rings. 

FIG.  44.    A  portion  of  a  duct  from  the  leafstalk  of  Celery ;  the  lower  part  annular;  the 
middle  reticulated,  and  the  thread  at  the  upper  part  broken  up  into  short  pieces. 

FIG.  45.    A  simple  spiral  vessel,  torn  across,  with  the  thread  uncoiling.    46.  Two  such  ves- 
sels joined  at  their  pointed  extremities. 

FIG.  47.    A  compound  spiral  vessel,  partially  uncoiled,  from  the  Banana. 

5 


50  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

only  by  the  form  of  the  markings ;  and  these  vary  so  greatly  in 
the  same  tissue,  and  even  in  the  very  same  duct  (Fig.  44),  that  it 
would  be  an  endless  and  useless  task  to  describe  all  their  varieties. 
A  continuous  dotted  duct  with  oblong  spots  is  nearly  the  same  as 
the  large  ducts  with  rather  larger  markings,  disposed  so  as  to  form 
a  series  of  regular  bands,  which  abound  in  Ferns  (Fig.  42).  When 
the  markings  are  a  little  longer,  and  the  walls  are  rendered  pris- 
matic by  mutual  pressure  (as  in  parenchyma)  we  have  the  Scala- 
riform  Ducts  of  Ferns  (Fig.  41),  so  named  because  the  lines  (or 
slits  as  they  become  in  old  tissue)  form  transverse  bars  i-esembling 
the  rounds  of  a  ladder.  In  many  cases,  it  is  uncertain  whether  the 
lines  or  narrow  bands  are  spots  thinner  than  the  rest  of  the  wall, 
as  they  certainly  are  in  dotted  ducts,  and  probably  in  the  scalari- 
form  vessel ;  or  whether  they  are  places  where  the  secondary 
deposit  is  thickened.  Probably  there  are  Reticulated  Ducts  (those 
where  the  lines  branch  and  run  together  here  and  there,  forming  a 
network)  of  both  sorts  ;  —  certainly  of  the  latter ;  for  we  occasion- 
ally meet  with  such  markings  (as  in  the  middle  of  Fig.  44)  on  a 
part  of  the  walls  of  true 

60.  Amnilar  and  Spiral  Ducts  (Trachece).  The  nature  of  their 
markings  is  explained  in  Paragr.  46.  They  are  elongated  cells 
(or  ducts  formed  by  the  confluence  of  several  cells),  with  their 
delicate  membranous  walls  strengthened  by  the  deposition  of  fibres 
within.  Sometimes  the  fibre  is  deposited  in  unbroken  rings  (as  in 
the  middle  of  Fig.  43,  and  in  Fig.  48,  d),  which  forms  the  Annular 
Duct.  More  commonly  it  is  deposited  as  a  continuous  spiral  coil, 
producing  the  Spiral  Duct  or  Spiral  Vessel  (Fig.  45-47) ;  which 
is  taken  as  the  typical  or  pattern  form  of  vascular  tissue,  because 
of  its  universal  occurrence  in  Flowering  Plants,  and  because  of  the 
general  tendency  of  such  definite  secondary  deposits  to  assume  a 
spiral  form.  That  these  markings  are  thickened,  and  not  thinner 
lines,  is  well  shown  in  those  remarkable  cells  from  Cacti,  already 
described  (Fig.  29,  30),  in  which  the  fibre  thickens  into  a  band,  with 
its  edge,  as  it  were,  applied  to  the  wall :  also  in  those  cells  which 
have  a  loose  spiral  fibre  generated  within  (48).  Moreover,  in 
what  is  called  the  true  Spiral  Vessel  (Fig.  45-47),  the  fibre  is  so 
strong  and  tough,  in  comparison  with  the  delicate  cell-wall  on 
which  it  is  deposited,  that  it  may  be  torn  out  and  uncoiled  when 
the  vessel  is  pulled  asunder,  the  membrane  being  destroyed  in  the 
operation.     This  is  seen  by  breaking  almost  any  young  shoot  or 


VASCULAR    TISSUE. 


51 


leafstalk,  or  the  leaf  of  an  Amaryllis,  and  gently  separating  the 
broken  ends ;  when  the  uncoiled  threads  appear  to  the  naked  eye 
like  a  fine  cobweb.  In  stems  furnished  with  pith,  the  spiral  ves- 
sels usually  occupy  a  circle  immediately  around  it.  They  occur 
also  in  the  veins  of  the  leaves,  and  in  all  parts  which  are  modifi- 
cations of  leaves.  More  commonly  the  spire  is  formed  of  a  single 
fibre,  as  in  Fig.  45,  46 :  it  rarely  consists  of  two  fibres ;  but  not 
uncommonly  of  a  considerable  number,  forming  a  band,  as  in  Fig. 
47.  Such  Compound  Spiral  Vessels  are  to  be  found  in  an  Aspara- 
gus shoot ;  and  are  finely  seen  in  the  stems  of  the  Banana,  from 
which  the  fibres  may  be  extracted  in  large  quantities.  From  the 
Musa  textilis  of  Manilla,  of  the  same  genus  as  the  Banana,  these 
cobwebby  fibres  are  procured  and  used  in  the  production  of  the 
most  delicate  of  textile  fabrics.  By  comparing  Fig.  47  with  Fig. 
42,  we  may  readily  perceive  that  the  wall  of  those  ducts  in  Ferns 
which  tear  into  a  band  when  pulled  asunder  may  have  an  indis- 
tinct spiral  deposit,  composed  as  it  were  of  a  band  of  fibres  that 
are  confluent  into  a  lining,  but  are  individually  separated  at  points, 
so  as  to  leave  interstices  in  the  form  of  bars,  &c. 

61.  These  ducts  or  vessels  usually  have  tapering  extremities 
(Fig.  45-47),  as  in  prosenchyma.  Like  prosenchyma,  they  vary 
greatly  in  length  ;  some  of  them  are  barely  oblong  or  cylindrical, 
and  are  manifestly  only  simple  cells,  of  the  same  character  as  the 
fibrous- walled  cells  formerly  mentioned  (46,  Fig.  26,  29),  which  no 
one  would  think  of  calling  vessels.  Others, 
though  still  nothing  but  single  cells,  are  more 
prolonged.  But  those  which  form  tubes  of 
much  greater  length  usually  consist  (as  their 
development  shows),  like  dotted  ducts,  of  a 
row  of  cells  formed  by  multiplication  (32-34, 
and  therefore  produced  from  one  cell),  with  the 
intervening  walls  obliterated,  so  as  to  give  a 
continuous  calibre.  This  origin  is  well  shown 
in  some  of  the  spiral  ducts  in  Fig.  48  (a,  &,  c), 
which  are  conspicuously  jointed,  or  composed 
of  a  series  of  cells  directly  confluent  by  their 


FIG.  48.  A  bundle  of  spiral  ducta  from  the  stem  of  Polygonum  orientale,  magnified:  a,  one 
composed  of  short  cells  and  with  the  fibre  closely  coiled ;  the  next,  fj,  is  composed  of  much 
longer  joints  and  has  a  very  loose  coil :  c  is  short-jointed,  and  the  fibre  of  the  loose  coil  is  oc- 
casionally forked:  rf  and  e  show  no  appearance  of  joints 'or  partitions,  and  the  turns  of  the 
spiral  fibre  are  still  more  remote. 


52 


THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 


abrupt  extremities.  Even  the  pointed  overlapping  ends  of  two 
contiguous  ducts  frequently  communicate  at  maturity,  by  the  ob- 
literation of  the  membrane  between  the  coils  of  the  fibre.  The 
turns  of  the  spiral  fibre  are  more  commonly  close,  as  in  Fig.  48,  a; 
but  they  are  often  separated,  even  widely,  as  if  the  thread  had 
been  extended  by  the  elongation  of  the  cell  after  the  spiral  deposi- 
tion had  been  formed.  Fig.  48  exhibits  several  degrees  of  this,  in 
different  vessels  of  the  very  same  bundle. 

62.  Interlaced  Fibrilliform  Tissue.  This  is  quite  as  distinct  from 
ordinary  cellular  tissue,  and  as  worthy  of  a  special  name,  as  is 
any  sort  of  the  so-called  vascular  tissue  of  plants.  It  is  the  more 
worthy  of  notice  from  its  near  resemblance  to  ordinary  forms  of 
animal  tissue.  It  consists  of  very  long  and  much  attenuated,  sim- 
ple or  branching,  fibre-like  cells,  or  strings  of  cells,  inextricably 
entangled  or  interwoven  without  order,  so  as  to  make  up  a  loose, 
fibrous  tissue.  It  is  principally  met  with  in  Fungi,  Moulds,  &c., 
where  the  cells  are  extremely  soft  and  destructible ;  and  in  Li- 
chens (Fig.  15),  where  it  is  dry  and  much  firmer. 

63.  Laticiferous  Tissue.  ( Vessels  of  the  Latex  or  Milky  Juice. 
Cinenchyma  of  Morren  and  Lindley.)  This,  the  only  remaining 
kind  of  vegetable  tissue,  is  of  an  ambiguous  character.  It  consists 
of  long  and  irregularly  branching  tubes  or  passages,  lying  in  no 
definite  position  with  respect  to  other  tissue,  and  when  young  of 
such  extreme  tenuity  (their  average  diameter  being  less  than  the 

fourteen-hundredth  of  an 
inch)  and  transparency  that 
they  are  hardly  visible,  even 
under  powerful  microscopes, 
except  by  particular  manip- 
ulation. But  their  older 
trunks  are  much  larger  than 
this,  when  gorged  with  the 
milky  or  other  special  juices 
which  it  is  their  ofl^ice  to 
contain,  and  when  their 
sides  are  thickened  by  the  deposition  of  such  matters.  Another' 
peculiarity  is,  that  they  anastomose  or  inosculate,  forming  a  sort  of 
network  by  the  union  of  their  branches,  like  the  veins  of  animals, 

FIG.  49.    Vessels  of  the  latex,  ramifying  among  cellular  tissue,  in  the  Dandelion ;  and  50, 
older  and  larger  vessels  from  the  same  plant }  all  highly  magnified. 


LATICIFEROUS    TISSUE.  53 

SO  that  there  is  a  free  communication  throughout  the  whole  sys- 
tem. The  articulations  which  they  often  present  (as  in  the  upper 
part  of  Fig.  50)  seem  to  prove  that  they  are  formed  by  the  con- 
fluence of  cylindrical  cells.  It  appears  altogether  most  probable, 
however,  that  the  true  view  of  these  vessels  is  that  maintained  by 
Meyen,  Mohl,  Schleiden,  and  Henfrey  ;  namely,  that  they  are  nei- 
ther proper  tissue,  nor  composed  of  cells  at  all ;  but  are 'mere  pas- 
sages formed  in  the  intercellular  spaces,  and  which  in  time  ac- 
quire a  proper  membrane  by  deposition  from  the  contained  fluid. 
In  this  respect,  therefore,  these  vessels  may  be  justly  compared 
with  the  veins  of  animals ;  but  the  circulation  which  Schultz,  the 
discoverer  of  this  tissue,  so  elaborately  described,  has  been  shown 
to  have  no  existence.  There  is  merely  a  mechanical  flow  from  a 
part  subject  to  pressure,  or  towards  a  place  where  the  latex  is 
escaping.  These  vessels  are  found  in  the  bark,  especially  in 
the  liber,  in  the  leafstalks,  and  in  the  leaves.  They  are  most 
numerous  or  conspicuous  in  those  plants  in  which  the  fluid  they 
contain  becomes  white  or  colored,  that  is,  in  those  which  have  a 
milky  juice. 

64.  All  the  different  kinds  of  tissue  that  enter  into  the  composi- 
tion of  the  plant  have  now  been  described,  and  referred  to  the  cell 
as  their  original.  Every  plant  or  each  organ  consists  at  first  of 
one  or  more  cells  of  proper  cellular  tissue ;  each  doubtless  com- 
mencing with  a  single  specialized  cell.  In  many  of  the  simpler 
vegetables,  the  cells  multiply  in  this  primitive  form  solely ;  and 
the  fully  developed  plant  consists  o^ parenchyma  alone.  But  in  all 
plants  of  the  higher  grades,  some  of  them  early  assume  the  forms 
or  undergo  the  transformations  by  which  they  give  rise  to  woody 
tissue,  ducts,  or  vessels.  All  these  various  sorts  of  modified  cells 
lie  vertically  in,  or  conspire  to  form  bundles  or  cords  that  run 
lengthwise  through,  the  stem  or  other  organ  they  occur  in  ;  so  that 
they  may  be  collectively  called  the  Vertical  System  or  Longitudinal 
System  (56).  They  accompany  each  other,  and  together  make  up 
the  woody  parts,  as  in  the  wood  proper,  in  the  liber  or  inner  bark, 
and  in  the  fibrous  framework  of  the  leaves.  And,  while  the  various 
kinds  run  into  each  other  through  every  manner  of  intermediate 
forms  (as  in  the  wood  of  the  Yew,  for  instance,  54),  the  whole, 
taken  together,  compose  tissues  which  are  almost  always  manifest- 
ly different  from  the  parenchyma  in  which  they  are  imbedded.  It 
is  convenient,  therefore,  to  give  to  these  the  collective  name  of 
5* 


54  THE    ELEBIENTARY    STRUCTURE    OF    PLANTS. 

Fibro -vascular  Tissues,  or  the  Fibro-vascular  System,  as  distin- 
guished from  the  Horizontal,  Parenchymatous,  or  common  Cel- 
lular System  of  the  plant. 

65.  Intercellular  System.  The  only  exception,  if  such  it  be,  to 
the  statement  that  all  the  vegetable  tissues  are  formed  of  cells,  is 
that  of  the  so-called  vessels  of  the  latex,  which,  according  to  the 
view  now  best  supported  (63),  do  not  so  originate,  but  are  a  secon- 
dary formation,  resulting  from  the  transudation  of  peculiar  assimi- 
lated matters  into  the  interspaces  between  the  cells  ;  and  are  there- 
fore rather  to  be  classed  with  other  receptacles,  canals,  or  inter- 
vals that  are  found  among  or  between  the  cells.  Some  of  these 
are  due  to  imperfect  contact  or  cohesion,  and  are  in  some  sort 
accidental,  or  at  least  are  irregular  and  indefinite  :  such  are 
the  Intercellular  Spaces  or  Passages,  left  when  the  angles  in 
parenchyma  do  not  accurately  fit  throughout.  Such  are  the 
larger  and  irregular  winding  passages  in  the  looser  tissues  called 
merenchyma  (51),  as  in  the  lower  stratum  of  the  leaf  (Fiff.  7),  or 
those  formed  by  the  lobed  or  branching  shape  of  the  cells  them- 
selves, so  disposed  hs  to  join  each  other  only  by  their  extremities, 
as  is  seen  in  many  water-plants.  These  spaces  are  soon  filled 
with  air.  There  are  besides,  in  the  stems  and  foliage  of  aquatic 
and  marsh  plants,  an  abundance  of  much  larger  Air-cells  or 
Air-passages,  usually  of  many  times  greater  diameter  than  the 
cells  of  the  tissue,  and  produced  by  their  particular  arrangement. 
These  are  as  elaborately  built  up  as  any  proper  organ  can  be,  are 
constructed  upon  a  uniform  plan  in  each  species,  and  are  evidently 
essential  to  its  existence,  such  plants  requiring  a  full  supply  of  air 
in  their  interior.  Other  air-spaces  or  empty  intervals,  apparently 
less  essential  to  the  life  of  the  plant,  arise  from  the ,  destruction  of 
a  part  of  the  parenchyma,  either  by  absorption,  or  by  distention, 
from  the  more  rapid  enlargement  of  the  outer  part.  In  this  way, 
the  stem  or  the  pith  of  many  plants  becomes  hollow. 

G6,  Receptacles  of  Special  Secretions.  These  arise  from  the  ex- 
udation of  the  proper  juices  of  the  cells  into  the  intercellular  pas- 
sages, which  are  distended  by  the  accumulation ;  and  often  the 
contiguous  cells  are  destroyed,  so  as  to  form  cavities  of  considera- 
ble size.  Such  are  the  turpentine  canals  of  the  Pines,  &c. ;  the 
oil-cells  of  the  fruit  of  the  Umbelliferae,  and  in  the  rind  of  the 
orange  and  lemon  ;  the  latex-canals  in  Sumach,  &c. 

67.  Internal  Glands,  such  as  those  which  form  the  translucent 


EPIDERMAL    SYSTEM.  '        55 

dots  in  the  leaves  of  the  Orange  and  Myrtle,  are  compact  little 
clusters  of  cells  filled  with  essential  oil. 

68.  Epidermal  System.  In  most  plants,  except  of  the  lowest 
grades,  the  superficial  layer  or  layers  of  cells  are  different  from 
those  they  envelope.  Also  certain  appendages  grow  from  the 
surface,  which  may  be  briefly  noticed  here. 

69.  The  Epidermis,  or  skin  of  the  plant,  is  formed  of  one  or  more 
layers  of  empty  cells,  with  thick  walls,  cohering  so  as  to  form  a 
firm  and  close  membrane,  which  may  be  torn  off  from  the  subja- 
cent tissue.  It  covers  all  parts  of  the  plant  that  are  directly  ex- 
posed to  the  air,  except  the  stigma.  Its  structure  and  office  will 
be  more  particularly  described,  (and  the  nature  of  what  has  been 
specially  termed  the  Cuticle  explained,)  in  the  chapter  on  the 
leaves. 

70.  Stomates  (Stomata),or  Breathing-pores,  are  orifices  connect- 
ed with  a  peculiar  structure  in  the  epidermis  of  leaves  and  other 
green  parts :  their  structure  and  office  will  likewise  be  described 
in  the  chapter  on  the  leaves,  to  which  organ  they  more  particu- 
larly belong. 

71.  Hairs  are  exterior  prolongations  of  cells  of  the  epidermis, 
consisting  either  of  single  elongated  cells,  or  of  several  cells  placed 
end  to  end,  or  of  various  combinations  of  such  cells.  They  are 
simple  or  branched,  single  or  clustered  (stellate,  &;c.),  and  exhibit 
the  greatest  variety  of  forms.  They  are  called  Glandular  Hairs 
when  the  upper  cell  or  cluster  of  cells  elaborates  peculiar  (usually 
odorous)  products,  such  as  the  fragrant  volatile  oil  of  the  Sweet 
Brier. 

72.  Glands.  This  name  is  applied  to  any  secreting  apparatus, 
like  glandular  hairs,  only  not  raised  on  a  stalk ;  and  also  to  other 
superficial  appendages  of  diverse  kinds. 

73.  Bristles  {Setce)  are  rigid,  thick-walled  hairs,  usually  of  a  sin- 
gle cell.  But  the  name  is  likewise  given  to  any  setiform  body,  of 
whatever  nature. 

74.  Prickles  are  larger  and  indurated  sharp-pointed  processes  of 
the  epidermis;  such  as  those,  of  the  Rose  and  Blackberry. 

75.  Stings,  or  Stinging  Hairs,  such  as  those  of  the  Nettle,  gener- 
ally consist  of  a  rigid  and  pointed  cell,  terminating  in  an  expanded, 
globular  base,  which  secretes  an  irritating  fluid. 

76.  Scurf,  or  Lepidote,  Scale-like  Hairs,  are  flattened,  star-like 
clusters  of  cells,  united  more  or  less  into  a  flat  scale,  which  is  fixed 


56  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

by  its  centre  to  the  epidermis.  They  are  well  shown  in  the  Ole- 
aster, Shepherdia,  and  most  silvery  leaves  like  theirs.  Our  spe- 
cies of  Vesicaria  exhibit  beautiful  gradations  between  these  and 
stellate  hairs. 


Sect.  IV.     Of  the  Contents  of  the  Tissues. 

77.  These  comprise  all  the  products  of  plants,  and  the  materials 
they  take  in  from  which  these  products  are  elaborated.  To  treat 
of  them  fully  would  anticipate  the  topics  which  belong  to  the 
chapter  on  nutrition.  Some  of  the  contents  of  cells,  however, 
have  already  been  mentioned,  in  the  account  of  their  production 
and  growth  (27-39):  others  require  a  brief  notice  here,  espe- 
cially two  solid  products  which  are  of  nearly  universal  occurrence 
and  great  importance  in  the  vegetable  economy,  namely.  Chloro- 
phyll and  Starch ;  and  a  third,  which,  however  constant,  may  be 
regarded  as  a  kind  of  accidental  deposit,  namely,  Raphides  or 
Crystals. 

78.  The  same  cells  contain  liquids,  solids,  and  air,  at  different 
ages.  Growing  and  vitally  active  cells  are  filled  with  liquid  (at 
least  while  vital  operations  are  carried  on),  namely,  with  water 
charged  more  or  less  with  nutritive  assimilated  matters,  the  pre- 
pared materials  of  growth  (11,  27).  Any  gaseous  matter  they 
may  contain  at  this  period  is,  for  the  most  part,  held  in  solution. 
Completed  cells  may  still  be  filled  with  liquid,  or  with  air  or  solid 
matter  only.  The  liquid  contents  of  the  vegetable  tissues,  of  what- 
ever nature  or  complexity,  are  often  spoken  of  under  the  common 
name  of 

79.  Sap.  In  employing  this  name  we  must  distinguish,  first, 
Crude  Sap  ;  the  liquid  which  is  imbibed  by  the  roots  and  carried 
upwards  through  the  stem.  This  is  water,  impregnated  with  cer- 
tain gaseous  matters  derived  from  the  air,  and  with  a  minute  por- 
tion of  earthy  matter  dissolved  from  the  soil.  It  is  therefore  inor- 
ganic (12).  But,  as  it  enters  the  roots  and  traverses  the  cells 
m  Its  ascent,  it  mingles  and  necessarily  becomes  impregnated 
with  the  liquid  or  soluble  assimilated  matters  which  these  contain 
(37).  On  reaching  the  leaves,  the  inorganic  materials  are  trans- 
formed, under  the  influence  of  light,  into  organizable  or  assimilat- 
ed matter;  and  the  liquid,  thus  charged  with  the  ready  prepared 
materials  of  growth,  is  now  Elaborated  Sap.     The  two  classes  of 


CONTENTS    OF    THE    TISSUES.  57 

DUtritive  matter  thus  produced,  and  which  all  forming  and  vitally 
active  cells  necessarily  contain,  namely  the  ternary  (of  which  su- 
gar and  dextrine  are  representatives),  and  the  quaternary  (pro- 
teine,  protoplasm,  &c.),  have  already  been  mentioned  (27). 

80.  Proper  Juices,  Caoutchouc,  Esseutial  Oils,  Turpentines,  &c.  Of 
the  peculiar  products  of  plants,  which  occur  under  an  infinite  va- 
riety of  forms  in  different  species,  it  is  only  needful  to  say  here, 
that  they  doubtless  arise  from  one  or  the  other  of  the  two  classes 
of  assimilated  matter  just  mentioned,  by  chemical  transforn^ations 
which  throw  them  out  of  the  ranks  of  nutritive  bodies.  They  seem 
to  be  turned  to  no  account  in  vegetable  growth ;  they  undergo 
changes  on  exposure  to  the  air,  by  which  they  become  resins, 
gums,  wax,  &c. ;  they  incline  to  extravasate  into  intercellular  spa- 
ces or  into  cavities  of  dead  or  effete  tissues,  or  to  be  directly  ex- 
creted from  the  surface.  So  that  we  may  regard  them  all,  per- 
haps, as  of  the  nature  of  excretions,  even  where  they  are  stored 
up  in  the  interior  of  the  plant.  For  we  must  remember  that  the 
vegetable  has  no  organs  or  apparatus  for  eliminating  and  casting 
out  excfreted  matters,  except  to  a  very  limited  extent  by  a  few  su- 
perficial glands,  which  are  found,  in  some  plants  and  in  some 
organs  only.  Caoutchouc  exists  in  the  form  of  minute  globules,  dif- 
fused as  an  emulsion  in  the  milky  juice  of  plants,  most  abundantly 
in  Urticaceee,  Euphorbiaceas,  and  Apocynacese.  Gutta  percha  is 
a  similar  product  of  the  milky  juice  of  a  Sapotaceous  plant. 

81.  Starch  (Farina,  Fecula)  is  one  of  the  most  important  and 
universal  of  the  contents  of  cells,  in  which  it  is  often  accumulated 
in  great  quantity,  so  as  to  fill  them  completely  (Fig.  52),  as  in 
farinaceous  roots, 
seeds,  &;c.  It  oc- 
curs in  the  pa- 
renchyma of  al- 
most every  part 
of  the  plant,  ex- 
cepting the  epi- 
dermis :  but  while  chlorophyll  is  nearly  restricted  to  the  superfi- 
cial parts,  directly  exposed  to  the  light,  starch  is  most  abundant 

FIG.  51.  Two  cells  of  a  potato,  with  some  contained  starch-grains,  highly  magnified;  one 
of  the  cells  contains  a  few  cubical  crystals  also. 

FIG.  52.  A  minute  portion  of  Indian  meal,  strongly  magnified;  the  cells  absolutely  filled 
with  grains  of  starch. 


58  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

in  internal  or  subterranean  parts,  most  concealed  from  the  light, 
as  in  roots  and  tubers,  the  pith  of  stems,  and  seeds.  Starch 
consists  of  oval  or  rounded  grains,  usually  somewhat  irregular  in 
outline,  and  sometimes  becoming  polyhedral  by  mutual  pressure, 
as  in  rice.  The  size  of  the  grains  varies  extremely  in  different 
plants,  and  even  in  the  same  cell ;  as  in  the  potato,  where  the 
larger  grains  measure  from  ^^^  to  -^^tj  of  an  inch  in  their  larger 
diameter,  but  the  smallest  only  ^:fV(y  of  ^^  inch.  In  wheat- flour 
the  larger  grains  are  ^^^  to  ^^^r  of  an  inch  in  diameter.  And  the 
largest  starch-grains  known  are  -^^u  of  an  inch  long.  Indeed, 
from  their  manner  of  growth,  we  might  expect  that  their  bulk 
would  be  somewhat  indefinite.  The  mode  of  their  formation  is 
indicated  by  the  peculiar  markings,  by  which  starch-grains  may 
almost  always  be  recognized  ;  namely,  by  the  dot  or  darker  point 
which  is  seen  commonly  at  one  end  of  the  grain,  and  the  fine 
concentric  lines  drawn  around  it,  which  present  the  appearance 
of  a  succession  of  irregular  circles  over  the  whole  surface,  in 
whatever  direction  the  grain  is  turned.  These  appearances  are 
best  seen  in  starch  from  the  potato,  one  of  the  most  characteristic 
forms  and  easiest  to  be  examined,  under  a  magnifying  power  of 
from  250  to  500  diameters  (Fig.  51).  The  chemical  composition 
of  starch  is  exactly  the  same  as  that  of  cellulose  (27) ;  and  the 
grains  are  solid  throughout,  but  their  interior  usually  softer  or  more 
gelatinous.  The  lines,  therefore,  it  is  evident,  mark  the  concen- 
tric layers,  or  hollowed  scales,  of  different  density,  which  are  suc- 
cessively deposited  on  an  original  nucleus.  The  dot  (or  hilum,  as 
it  has  been  called)  that  indicates  the  position  of  the  nucleus,  be- 
comes a  concavity,  from  its  not  receiving  a  part  of  the  successive 
deposits,  which  are  greatest  on  the  opposite  side,  or  very  eccentric. 
The  grains  lie  loose  in  the  cell,  and  are  probably  formed  so ; 
although  it  is  thought  by  some  that  the  nucleus  or  hilum  was  in 
contact  with  the  cell-wall,  so  that  the  increase  by  deposition  must 
necessarily  have  taken  place  on  the  other  sides.  On  the  whole, 
there  is  reason  to  conclude  that  starch-grains  are  formed  on  nuclei 
or  cytoblasts,  that  is,  on  minute  solidified  portions  of  protoplasm, 
like  those  from  which  cells  primarily  originate,  by  the  deposition 
of  layer  over  layer  of  ternary  assimilated  matter  (dextrine,  &c.), 
essentially  like  that  which  constitutes  the  secondary  deposit  that 
thickens  the  cell-membrane  (39).  Their  origin,  therefore,  would 
be  closely  analogous  to  that  of  cells  formed  ''directly  from  a  cy- 


CONTENTS    OF    THE    TISSUES.  59 

toblast  in  the  manner  propounded  by  Schleiden ;  only  that  the 
deposit  in  the  case  of  starch  is  exogenous^  by  layer  over  layer  upon 
a  solid  nucleus ;  while  in  the  cell  it  is  endogenous^  or  by  layer 
within  layer,  lining  the  walls.  In  both,  the  solidified  matter  is  in- 
soluble in  cold  water;  but  in  starch  it  dissolves  (or  rather  swells 
up  into  a  jelly)  and  is  diffused  in  boiling  water.  The  deposit  on 
the  walls  of  the  cell  is  of  various  degrees  of  density,  and  some- 
times exhibits  the  chemical  peculiarity  of  starch.  Though  usually 
permanent,  probably  it  is  sometimes  redissolved,  to  be  appropri- 
ated elsewhere.  But  starch  is  a  temporary  formation,  for  future 
use  ;  in  which  respect  it  may  be  compared  with  the  fat  of  animals. 
When  required  for  nutrition,  the  grains  are  restored  to  a  liquid 
state  in  the  plant,  at  the  natural  temperature  ;  that  is,  they  are  re- 
converted into  Dextrine^  —  a  modification  of  the  same  substance 
which  is  soluble  in  cold  water,  —  and  this  passes,  in^part,  at  least, 
into  Sugar,  which  is  still  more  soluble ;  and  thus  a  syrup  is  form- 
ed, which  the  sap  dilutes  and  conveys  to  the  adjacent  parts  wher- 
ever the  process  of  growth  is  going  on.  Physiologically  consid- 
ered, therefore,  starch  is  unappropriated  cellulose,  stored  up  in  a 
particular  form,  as  the  ready-prepared  material  of  new  tissues  : 
while  dextrine  and  sugar  are  forms  in  which  the  same  unazotized 
assimilated  matters  are  prepared  for  the  immediate  purposes  of 
nutrition.  The  part  which  these  substances  play  in  the  vegetable 
economy  will  be  more  fully  explained  elsewhere. 

82.  A  distinguishing  character  of  starch  is  that  it  is  turned  blue 
or  deep  violet  by  iodine,  even  in  the  most  dilute  solution.  Starch- 
grains  are  usually  simple  and  separate  ;  but  occasionally  two  or 
more  young  grains  join,  and  are  enwrapped  by  new  layers  into 
one.  In  some  plants  the  grains  regularly  cohere  in  united  clus- 
ters. Compound  grains  of  the  kind  are  seen  in  West  Indian  Ar- 
row-root, the  corms  of  Colchicum,  Arum,*  &c.  The  starch-grains 
are  nearly  uniform  in  the  same  plant  or  organ,  and  of  very  differ- 
ent appearance  in  diflferent  plants :  so  that  the  smallest  quantity  of 
starch  from  the  potato,  wheat,  rice,  maize,  &c.,  may  at  once  be 
distinguished  under  the  microscope. 

83.  Vegetable  Jelly  {Bassorin,  Salep,  Pectine,  Vegetable  Mucilage 


The  rootstocks  of  Brasenia  and  Nymphsea  exhibit  oblong  or  club-shaped 
compound  starch  grains  of  great  size,  very  much  like  those  from  Arum,  rep- 
resented by  Schleiden,  on  page  17,  Engl.  Translation. 


60  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

in  part)  has  the  chemical  composition  and  nearly  the  properties  of 
starch  after  it  has  been  diffused  in  hot  water.  It  is  not  only  one 
of  the  contents  of  cells,  as  in  the  tubers  of  Orchises,  in  many 
fruits,  &c.,  and  largely  in  those  of  Algse,  but  it  also  forms  in  great 
part  the  cell-wall  of  Algae,  as  in  the  Carragheen  Moss  (Chondrus 
crispus),  from  which  vegetable  jelly  is  obtained  for  culinary  pur- 
poses. When  dry,  it  is  horny  or  cartilaginous;  when  moist,  it 
swells  up,  becomes  gelatinous,  and  is  capable  of  being  diffused 
perfectly  through  cold  water.  It  passes  by  various  modifications, 
on  the  one  hand  into  cellulose,  and  on  the  other  into  starch  and 
dextrine.  We  have  it  as  an  excretion  in  Gum  Tragacanth.  True 
gums,  such  as  Gum  Arabic,  &;c.,  are  altered  states  of  the  same 
substance,  or  of  dextrine,  and  are  likewise  formed  only  as  ex- 
cretions. 

84.  Sugar  (of  which  there  are  two  distinct  kinds.  Cane  and  Grape 
Sugar)  is  the  most  soluble  of  the  many  forms  of  ternary  organiza- 
ble  matter,  as  already  stated.     Though  sometimes  crystallized  as ' 
an  excretion  in  the  nectaries  of  flowers,  yet  in  the  plant  it  exists 
only  in  solution.     It  abounds  in  growing  parts,  and  in  pulpy  fruits. 

85.  Fixed  Oils  belong  to  the  class  of  ternary  assimilated  products, 
but  they  contain  little  or  no  oxygen.  The  fatty  oils  take  the  place 
of  starch  (from  which  they  are  probably  formed)  in  the  seeds  of 
many  plants  (as  in  flax-seed,  walnuts,  &c.),  and  of  sugar  in  some 
fruits,  such  as  the  olive.  They  also  exist  in  the  herbage,  and  in 
some  smaller  proportion  in  the  cells,  perhaps,  of  almost  all  plants. 

86.  Wax  is  a  product  of  nearly  the  same  nature  as  the  fixed  oils, 
only  it  is  solid  at  the  ordinary  temperature,  which  is  extensively 
found  in  plants  as  an  excretion,  particularly  on  the  surface  of 
leaves  and  fruits,  forming  the  bloom  or  glaucous  surface  which 
repels  water,  and  so  prevents  such  surfaces  from  being  wetted.  It 
exists  largely  on  some  fruits,  as  the  bayberry.  As  bees  convert 
sugar  into  wax,  and  as  the  sugar-cane  yields  a  kind  of  wax  which 
"  sometimes  passes  into  sugar,"  we  may  infer  that  wax  is  formed 
in  the  vegetable  of  sugar  or  its  kindred  products.  Wax  also  exists 
as  one  of  the  contents  of  cells,  of  leaves  especially,  where  it  ap- 
pears to  form  the  basis  of 

87.  Chlorophyll,  the  substance  which*  gives  the  universal  green  col- 
or to  the  leaves  and  herbage.  It  is  formed  only  in  parts  exposed 
to  the  light,  such  as  the  green  bark,  and  especially  the  leaves ; 
not,  however,  in  the  external  layer  of  cells,  or  epidermis  (69),  but 


CONTENTS    OF    THE    TISSUES.  61 

in  the  parenchyma,  especially  in  the  superficial  strata.  It  consists 
of  minute  soft  granules,  of  no  particular  form,  either  separate  or  in 
clusters,  forming  grains  of  considerable  size,  which  lie  free  in  the 
cells,  or  loosely  adhere  to  their  sides.  They  often  adhere  to  the 
surface  of  starch-grains.  Indeed,  Mr.  Henfrey  plausibly  considers 
chlorophyll  to  arise  from  altered  starch  (with  the  evolution  of  oxy- 
gen) ;  which  is  the  more  likely,  as  it  is  said  to  appear  in  the  cells 
later  than  starch.*  It  belongs  to  the  class  of  waxy  bodies ;  and  is 
soluble  in  alcohol  or  ether,  but  not  in  water.  Chlorophyll  under- 
goes certain  changes,  in  autumn  foliage  especially,  by  which  it 
turns  to  red  or  yellow.  Chromule  is  a  name  applied  to  coloring 
matters  not  green,  and  mostly  in  a  liquid  form,  as  in  the  cells  of 
petals,  giving  to  them  their  peculiar  tints.  These  coloring  matters 
are  probably  a  mixture  of  very  various  products. 

88.  Alkaloids  (such  as  Morphine^  Strychnine^  and  Quinine)  are 
quaternary  products  of  plants,  principally  formed  in  the  cells  or 
interspaces  of  the  bark.  Unlike  the  proteine  compounds  (27,  79, 
gluten,  fibrine,  &c.),  they  appear  to  bear  no  part  in  vegetation,  but 
to  be  completed  results  of  vegetation,  and  therefore  of  excretory 
nature.  In  these  substances  reside  the  most  energetic  properties 
of  the  vegetable,  considered  as  to  its  action  on  the  animal  econo- 
my, the  most  powerful  medicines,  and  the  most  virulent  poisons. 
That  they  are  of  the  nature  of  excretions  may  be  inferred  from 
the  fact,  that  a  plant  may  be  poisoned  by  its  own  products. 

89.  Tannin  or  Tannic  Acid,  which  most  abounds  in  older  bark,  is 
probably  a  product  of  the  oxidation  or  commencing  decomposition 
of  the  tissues.  So,  also,  Humus^  Humic  Acid^  Ulmin,  Ulmic  Acid, 
and  the  numerous  related  substances  distinguished  by  the  chemists, 
are  products  of  further  decomposition  of  vegetable  tissue,  and  not 
products  of  vegetation. 

90.  Vegetable  Acids.  Tartaric,  Citric,  and  Malic  acids  are  the 
principal  kinds,  which  occur  in  leaves  and  those  succulent  stems 
which  have  a  sour  juice,  and  in  all  acidulated  fruits.  They  are 
ternary  products,  with  an  excess  of  oxygen.  Oxalic  Acid,  which 
is  an  almost  universal  vegetable  product,  is  a  binary  body,  differ- 
ing from  carbonic  acid  in  ultimate  composition  only  in  having  a 


*  In  that  case,  the  nitrogen  obtained  in  Mulder's  incomplete  analysis  (which 
gave  C^^,  H^^,  N^,  O^,  with  some  nitrogenous  matter  not  determined)  must 
belong  to  the  mucous  matter,  or  protoplasm,  which  invests  the  green  granules. 

6 


62  THE    ELEMENTARY    STRUCTURE    OF    PLANTS. 

small  proportion  more  of  oxygen.  (Hydrocyanic  or  Prussic  Acid 
is  one  of  the  special  products  peculiar  to  certain  plants,  and  of 
very  different  composition,  containing  a  large  proportion  of  nitro- 
gen.) These  vegetable  acids  do  not  appear  to  play  any  leading 
part  in  vegetation.  They  seldom  exist  in  a  free  state,  but,  are 
combined  with  the  alkaloids,  and  with  the  inorganic  or  earthy  al- 
kalies (Potash,  Soda,  Lime,  and  Magnesia)  which  are  introduced 
into  plants  from  the  soil  with  the  water  imbibed  by  the  roots. 
The  more  soluble  salts  thus  produced  are  found  dissolved  in 
plants  ;  the  more  insoluble  are  frequently  deposited  in  the  cells  in 
the  form  of 

91.  Crystals  or  Rapllides.  These  exist  in  more  or  less  abundance 
in  almost  every  plant,  especially  in  the  cells  of  the  bark  and  leaves, 
as  well  as  in  the  wood  and  pith  of  herbaceous  plants.  Far  the 
most  common,  and  the  principal  kind  formed  with  a  vegetable 
acid,  are  those  of  oxalate  of  lime.  In  an  old  stem  of  the  Old-man 
Cactus  (Cereus  senilis),  the  enormous  quantity  of  80  per  cent,  of 
the  solid  matter  left  after  the  water  was  driven  off  was  found  to 
consist  of  these  crystals.  In  the  thin  inner  layers  of  the  bark  of 
the  Locust,  for  example,  each  cell  contains  a  single  crystal,  as  is 
seen  in  Fig.  57.  And  Professor  Bailey,  who  has  devoted  particu- 
lar attention  to  this  subject,  computed  that,  in  a  square  inch  of  a 
piece  of  Locust-bark,  no  thicker  than  ordinary  writing-paper,  there 
are  more  than  a  million  and  a  half  of  these  crystals.  There  is 
frequently  a  group  of  separate  crystals  in  the  same  cell ;  or  a  con- 
glomerate cluster,  as  in  Fig.  58.  In  the  leaves  of  the  Fig,  and 
many  other  Urticaceous  plants,  a  globular  crystalline  mass  is  sus- 
pended in  the  cell  by  a  kind  of  stalk.  Oxalate  of  lime  crystal- 
lizes in  octahedra  (as  in  Fig.  56,  the  crystal  in  the  lower  right- 
hand  cell),  and  in  right-angled  four-sided  prisms  (as  in  Fig.  59, 
60),  with  variously  modified  terminations.  The  crystals  are  fre- 
quently acicular,  or  needle-shaped,  either  scattered  or  packed  in 
bundles  of  from  twenty  to  some  hundreds  (as  in  Fig.  53-55).  It 
is  to  this  form  that  the  name  of  Raphides  (which  is  the  Greek 
word  for  needles)  was  originally  applied,  and  to  which  it  properly 
belongs;  although  it  has  been  indiscriminately  extended  to  all 
kinds  of  crystals  which  occur  in  the  cells  of  plants.  In  the  com- 
mon Arum  or  Indian  Turnip,  as  well  as  in  the  Calla  iEthiopica  and 
other  plants  of  that  family,  the  crystal-bearing  cells  (Fig.  54)  may 
readily  be  detached  from  the  rest  of  the  tissue ;  and  when  mois- 


CONTENTS    OF    THE    TISSUES. 


tened  and  distended  by  endosmosis,  they  forcibly  discharge  their 
contents,  in  a  curious  manner,  from  an  orifice  at  each  end,  as  is 
shown  in  Fig.  55.     These  acicular  crystals  are  generally  thought 


to  consist  of  oxalate  of  lime  ;  according  to  Quekett,  they  are  phos- 
phate of  lime.  Of  other  crystals  composed  of  inorganic  acids  and 
an  earthy  base,  the  more  usual  are  rhombic  crystals  of  carbonate 
of  lime,  found  in  Cacti ;  and  tabular,  often  twin  crystals  of  sul- 
phate of  lime,  which  are  *'  found  in  the  Musacese  and  many  Scita- 
minese."  Such  are  wholly  formed  of  inorganic  materials,  derived 
from  the  soil. 

92.  Silex,  likewise  derived  from  the  soil,  very  generally  occurs 
as  a  part  of  the  deposit  or  incrustation  on  the  walls  of  cells  ;  *  but 
it  is  not  found  in  the  form  of  crystals  in  their  interior.  In  the  Dia- 
tomacese  nearly  the  whole  cell-wall  is  composed  of  this  indestruc- 
tible material ;  consequently,  the  remains  of  these  minute  organ- 
isms accumulate  at  the  bottom  of  the  water  in  which  they  live,  so 
as  to  form  immense  strata  in  many  places. 

*  This  may  be  shown  by  carefully  burning  off  the  organized  matter  of  the 
tissue,  and  examining  the  undisturbed  ashes  by  the  microscope. 

FIG.  53.  Raphides,  or  acicular  crystals,  from  the  stalk  of  the  Rhubarb :  three  of  the  cells 
contain  starch  or  chlorophyll,  and  two  of  them  raphides. 

FIG.  54.  Raphides  of  an  Arum,  contained  in  a  large  cell;  and  55,  the  same,  detached  from 
the  surrounding  tissue,  and  discharging  its  contents  upon  the  application  of  water. 

FIG.  56.     Crystals  from  the  Onion  ;  one  of  them  a  hemi trope. 

FIG.  57.    Crystals  of  the  inner  bark  of  the  Locust. 

FIG.  58,    A  glomerate  mass  of  crystals  from  the  Beet-root. 

FIG.  59,60.  Crystals  from  the  bark  of  Hickory.  Figures  55-60,  and  also  51,  are  from 
sketches  kindly  supplied  by  Professor  Bailey  of  West  Point. 


64         THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 

CHAPTER  II. 

OF  THE  GENERAL  MORPHOLOGy  OF  THE  PLANT. 

93.  The  Individual  Plant.  The  organic  elements,  or  cells  in 
their  various  forms,  which  have  been  treated  of  in  the  preceding 
chapter,  make  up  the  individual  plant.  Looking  now  upon  plants 
as  individual  beings,  we  observe  that  they  present  themselves  un- 
der the  greatest  variety  of  forms ;  some  of  them  are  of  the  utmost 
simplicity,  and  many  of  these  are  so  minute,  that  they  are  individ- 
ually undistinguishable  or  invisible  to  the  naked  eye,  and  only  be- 
come conspicuous  by  their  aggregation  in  great  numbers :  others 
are  highly  complex  in  structure,  and  attain  to  a  vast  size,  like  the 
giants  of  the  forest,  some  of  which  have  flourished  for  a  thousand 
years  or  more.  All  the  larger  vegetables  are  formed  of  a  count- 
less number  of  cells  ;  which,  as  they  increase,  arrange  them- 
selves so  as  to  shape  the  fabric  into  definite  parts,  such  as  stem, 
leaves,  and  roots,  each  having  distinct  offices  to  fulfil,  while  all  are 
subservient  to  the  nutrition  and  perfection  of  the  individual  whole. 
These  parts  are  called  the  Organs  of  the  plant ;  or,  more  techni- 
cally, the  Compound  Organs^  since  it  is  the  cells  of  which  they  are 
composed  that  are  the  real  instruments,  and  carry  on  the  opera- 
tions of  the  vegetable  economy.  These  organs  are  most  distinct, 
and  at  the  same  time  most  diversified,  in  the  highest  grade  of 
plants ;  in  the  lower,  they  are  successively  less  and  less  evolved, 
until  all  such  distinction  of  parts  vanishes,  and  the  plant  is  reduced 
to  a  rounded  or  flattened  mass  of  cells,  to  a  row  of  cells  strung  end 
to  end,  or  even  to  a  single  cell.  Since  these  last  are  the  simplest 
plants,  and  the  higher  acquire  their  more  complex  structure  (as 
will  hereafter  be  shown)  from  an  equally  simple  beginning,  the 
most  natural  order. for  exhibiting  the  principal  grades  of  vegeta- 
tion is  to  commence  with  the  lowest  and  simplest  possible  kinds, 
namely,  with 

94.  Plants  of  a  Single  Cell.  There  are  several  kinds  of  such 
plants  among  the  Algse  (Sea-weeds,  &c.),  which  rank  as  the  low- 
est order  of  the  vegetable  kingdom.  They  are  especially  interest- 
ing here,  because  they  furnish  the  readiest  illustrations  of  the  va- 
rious methods  of  cell-formation  which  have  been  described  in  the 


PLANTS    OF    A    SINGLE    CELL.  65 

preceding  chapter  (26-35).  For  in  them  vegetation  is  reduced 
to  its  simplest  terms :  the  plant  and  the  cell  are  here  identical. 
The  cell  constitutes  an  entire  vegetable  without  organs,  imbibing 
its  food  by  endosmosis  (37)  through  its  permeable  walls,  assimi- 
lating this  food  in  its  interior,  and  converting  the  organizable  prod- 
ucts at  first  into  the  materials  of  its  own  enlargement  or  growth, 
or  finally  into  new  cells  which  constitute  its  progeny.  Thus  we 
have  an  epitome  of  all  that  is  essential  in  vegetation,  even  on  the 
largest  scale,  namely,  the  imbibition  of  inorganic  materials ;  its 
assimilation  ;  its  application  to  the  growth  of  the  individual,  or  nu- 
trition,  and  the  formation  of  new  individuals,  or  reproduction. 
But  even  while  thus  organically  simple,  the  plant  is  not  restricted 
to  one  monotonous  pattern.  On  the  contrary,  different  species, 
each  in  its  own  uniform  manner,  develope  the  cell  and  give  rise 
to  their  progeny  in  all  the  various  ways  that  have  been  mentioned 
when  describing  the  forms  and  the  development  of  cells.  The 
simplest  case  is  that  of 

95.  1st,  Plants  of  a  Single  Globular  Cell;  that  is,  of  a  cell 
which  grows  equally  in  every  direction,  and  therefore  is  neither 
elongated  nor  branched.  Of  this,  the  microscopic  plant  known  as 
giving  rise  to  the  phenomenon  of  red  snow  (but  which  also  occurs 
on  damp  earth,  &c.)  furnishes  a  good  illustration.  Each  individ- 
ual is  a  single  cell  (Fig.  61),  which  quickly  attains  its  growth,  and 
produces  (by  original  cell-formation,  it  is 
thought)  a  considerable  number  of  minute 
free  cells  in  its  interior.  The  mature 
mother-cell  now  decays ;  and  the  new 
generation  it  contained  enlarge  into  simi- 
lar cells  or  plants,  which  give  rise  to  their 
progeny  and  perish  in  their  turn.  Some 
other  globular  one-celled  plants  (like  Chro- 
ococcus.  Fig.  63),  are  very  similar,  except  that  they  propagate  by 
division  of  the  whole  contents,  and  finely  illustrate  that  general 
process  of  free  cell-multiplication  (37).  The  layer  of  protoplasm 
which  lines  the  cell-wall  forms  a  constriction  in  the  middle,  and 

FIG,  61.  Several  individuals  of  the  Red-snow  Plant  (Protococcus  nivalis),  magnified.  62. 
An  individual  highly  magnified,  showing  more  distinctly  the  new  cells  or  spores  formed  with- 
in it. 

FIG.  63.  An  individual  of  Chroococcus  rufescens,  after  Nageli,  much  magnified.  64.  A 
more  advanced  individual,  with  the  contents  forming  two  new  cells  by  division.  65.  Another, 
with  the  contents  divided  into  four  new  cells. 

6* 


66         THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 

soon  separates  the  whole  inclosed  contents  into  two  parts ;  a  layer 
of  cellulose  is  at  the  same  time  deposited  on  the  surface,  and 
thus  two  new  cells  are  produced  (Fig.  64),  which  usually  subdi- 
vide each  into  two  (Fig.  65).  Four  new  cells  are  thus  formed 
within  a  mother-cell ;  and  the  latter  is  destroyed  in  the  process, 
all  its  living  contents  having  been  employed  in  the  formation  of 
the  progeny,  and  its  effete  wall  is  obliterated  by  softening  or  de- 
cay, or  by  the  enlargement  of  the  contained  cells.  Thus  this  sim- 
plest vegetation  goes  on,  from  generation  to  generation.  The  sof- 
tened remains  or  products  of  the  older  cells  often  accumulate  and 
form  a  gelatinous  stratum  or  nidus,  in  which  the  succeeding  genera- 
tions are  developed,  and  from  which  they  doubtless  derive  a  part 
of  their  sustenance,  —  just  as  a  tufted  moss  is  nourished  in  part 
from  the  underlying  bed  of  vegetable  mould  which  is  formed  of 
the  decayed  remains  of  its  earlier  growth.  One  step  in  advance 
brings  us  to 

96.  2d,  Plants  of  a  Single  Elongated  Cell ;  that  is,  of  a  cell 
which  grows  on  in  one  direction,  but  without  branching.     Such 

plants  answer  to  cells  of 
prosenchyma,  or  to  vessels 
(52,  57).  For  an  example 
we  may  take  any  species 
of  Oscillaria  (Fig.  66) ;  a 
form  of  aquatic  vegetation 
of  microscopic  minuteness, 
considered  as  to  the  size  of 
the  individuals,  but  which  rapidly  multiply  in  such  inconceivable 
numbers,  that,  at  certain  seasons,  they  sometimes  color  the  surface 
of  whole  lakes  of  a  green  hue,  as  suddenly  as  broad  tracts  of 
alpine  or  arctic  snow  are  reddened  by  the  Protococcus.* 

97.  3d,  Plants  of  an  Elongated  and  Branching  Cell.  Some 
elongated  cells  in  vegetable  tissue  fork  as  they  elongate,  and  be- 
come branched  ;  as  is  seen  in  Fig.  15.  Several  plants  consist  of 
individual  cells  of  this  kind ;  as,  for  example,  the  species  of  Vau- 
cheria,  which  form   one  kind  of  the   delicate  and    flossy  green 


*  If  the  transverse  markings  of  Oscillaria  arise  from  imperfect  partitions, 
then  the  plant  corresponds  to  the  duct  (58). 

FIG.  66.    Two  individuals  of  Oscillaria  spiralis,  magnified  :  one  of  them  with  one  extremi- 
ty cut  off. 


PLANTS    OF    A    SINGLE    CELL. 


67 


threads  which  abound  in  fresh  waters,  and  are  known  in  some 
places  by  the  name  of  Brook-silk.  These,  under  the  magnifying- 
glass,  are  seen  to  be  single  cells,  of  unbroken  calibre,  furnished 
with  branches  here  and  there  (Fig.  71).  The  branches  are  pro- 
trusions, or  new  growing  points,  which  shoot  forth,  and  have  the 
power  of  continuous  growth  from  the  apex.    In  Bryopsis  (Fig.  73), 


a  beautiful  small  Sea-weed,  the  branches  are  much  more  numerous 
and  regular :  they  are  often  constricted  where  they  join  the  main 
stem,  if  we  may  so  call  it,  but  the  cavity  continues  from  stem  to 
branch ;  or,  in  other  words,  the  whole  plant  consists  of  a  single 
vegetating  cell. 

98.  While  in  these  cases  the  ramifications  of  the  cell  imitate,  or 
as  it  were  foreshadow,  the  stem  and  branches  of  higher  organized 
plants,  we  have  in  Botrydium  (Fig.  70)  a  cell  whose  ramifications 
resemble  and  perform  the  functions  of  a  root.  This  is  a  terres- 
trial Alga,  with  a  rounded  body  composed  of  an  enlarged  cell, 
which  elongates  and  ramifies  downwards,  the  slender  branches 
penetrating  the  loose,  damp  soil  on  which  the  plant  grows,  exactly 
in  the  manner  of  a  subdivided  root.  Meanwhile,  a  crop  of  rudi- 
mentary new   cells  is  produced,  by  original  free  cell -formation 

FIG.  67-69.  Botrydium  Wallrothit"in  its  development,  and  with  new  cells  forming  within; 
after  Kiitzing:  67,  the  cell  still  spherical:  63,  pointing  into  a  tube  below:  69,  the  tube  pro- 
longed and  branched  :  all  much  magnified. 

FIG.  70.    Botrydium  argillaceum,  after  Endlicher;  the  full-grown  plant,  magnified. 

FIG.  71.  Vaucheria  clavata,  enlarged:  a,  a  spore  formed  in  the  enlarged  apex  of  that 
branch.     72.  End  of  the  branch,  more  magnified,  with  the  spore  escaped  from  the  burst  apex. 

FIG.  73.    Bryopsis  plumosa;  summit  of  a  stem  with  its  branchlets,  much  enlarged. 


68 


THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 


(28),  in  the  liquid  which  fills  the  body  of  the  mother-cell :  these, 
escaping  when  that  decays  or  bursts,  grow  into  similar  plants,  in 
the  manner  shown  by  Fig.  67  -  69. 

99.  The  new  cells  by  which  Vaucheria  is  propagated  are  pro- 
duced in  a  different  way ;  as  is  shown  in  V.  clavata  (Fig.  71,  72). 
The  apex  of  a  branch  enlarges  ;  its  green  contents  thicken,  sep- 
arate from  those  below,  and  a  membrane  of  cellulose  is  formed 
around  it,  just  as  it  forms  around  the  contents  of  the  whole  cell  in 
the  microscopic  Chroococcus  (Fig.  63),  but  no  further  division  takes 
place ;  the  wall  of  thB  mother-cell  bursts  open,  and  the  new-born 
cell  escapes  into  the  water.  When  it  grows,  it  elongates  a  little 
from  one  end,  and  by  this  fastens  itself  to  any  solid  body  it  rests 
on,  and  then  grows  from  the  opposite  end  into  a  prolonged  tube, 
with  occasional  branches,  like  its  parent.  In  this  way,  a  plant 
composed  of  a  single  cell  imitates  not  obscurely  the  downward  and 
upward  growth  (the  root  and  stem)  of  the  more  perfect  plants.  In 
the  foregoing  cases  we  noticed  that  the  production  of  new  cells  in- 
sured the  death  of  the  parent;  the  whole  living  contents  being  ap- 
propriated to  the  new  formation.  In  this  case,  the  progeny  origi- 
nates from  the  living  contents  of  a  part  of  the  cell  only,  and  the 
walls  of  that  portion  alone  perish. 

100.  Plants  of  a  Single  Row  of  Cells.     To  these  there  is  but  a  sin- 
gle step  from  plants  formed  of  a  single  cell  (whether  branching  or 
unbranched)  which  has  the  power  of  continuous  growth  from  the 
apex ;  and  that  step  consists  in  the  formation  of  transverse  parti- 
tions.     The    man- 
ner in  which  these 
are    produced    has 
been    already    de- 
scribed (Fig.  8),  as 
observed  in  a  spe- 
cies   of    Conferva. 
Most  of  these  sim- 
ple, thread-like  Al- 
gsD   are   composed 
of  a  single  row  of 

cells,  produced  in  this  way.  The  three"  kinds  of  Moulds  or  Mil- 
dew Fungi   here   represented   (Fig.  74-76)   consist,  as  to  the 


FIG.  74.    The  Bread-mould  (Mucor)  magnified.    75.  Aaother  Mould  (Penicillum  glaucum). 
76.  Botrytis  Bassiana,  a  parasitic  Mould :  all  magnified. 


PLANTS    OF   A    SINGLE    ROW    OF    CELLS.  69 

creeping  part  at  the  base  (which  spreads  widely  through  the  sub- 
stance they  live  on)  of  long,  thread-like,  and  usually  branching 
cells  (much  like  those  of  Fig.  15),  for  the  most  part  destitute  of 
partitions ;  while  the  upright  portions  are  composed  of  a  row  of 
short  cells,  like  those  of  a  Conferva.  These  are  terminated  in  the 
Bread-mould  (Fig.  74)  by  a  much  larger  cell,  which  developes 
numerous  and  very  minute  rudimentary  ones  in  its  interior.  In 
Fig.  75,  we  have  a  different  arrangement,  namely,  a  cluster  of 
branches,  made  up  of  a  series  of  bead-like,  easily  separable  cells, 
which  are  evidently  formed  by  the  process  of  division  just  illustrat- 
ed, and  which  serve  as  seeds  to  reproduce  the  species. 

101.  Spores.  When  the  cells  remain  connected  as  they  multi- 
ply, they  increase  the  size  or  complexity  of  the  individual  vegeta- 
ble. When  they  separate,  each  becomes  the  initial  cell  of  a  new 
plant.  Any  cell  is  capable  of  originating  a  new  individual.  No 
sooner,  however,  does  the  plant  acquire  such  slight  complex- 
ity as  to  consist  even  of  a  single  series  of  cells,  than  a  distinc- 
tion begins  to  appear  between  cells  adapted  for  vegetation^  and 
those  for  reproduction.  Both  may  propagate  the  species  :  the 
thread-like,  vegetating  cells  which  form  the  base  of  the  Moulds,  in 
Fig.  75,  for  example,  grow  with  the  same  readiness  as  the  minute, 
specialized  cells  which  terminate  this  simple  vegetation.  But  the 
first  appear  to  do  so  after  the  manner  in  which  the  higher  grades 
of  plants  multiply  by  offshoots  or  division  of  the  root ;  while  the 
second  are  analogous  in  this  respect  to  the  seeds  or  embryos  of 
such  higher  plants.  These  cells  specialized  for  propagation,  how- 
ever they  may  originate,  are  accordingly  distinguished  by  a  special 
name,  that  of  Spores  or  Sporules.  We  have  to  rise  still  higher 
in  the  scale,  however,  before  a  well-marked  distinction  can  be 
drawn  in  all  cases  between  cells  for  reproduction  and  cells  for 
vegetation. 

102.  Conjugation.  At  this  stage  of  vegetation,  however,  and 
even  in  a  large  tribe  of  plants  composed  of  single  and  simple  cells, 
a  process  of  great  physiological  importance  is  first  observed, — 
the  evident  equivalent  of  bisexuality  in  the  higher  orders,  —  by 
which  the  reproductive  cells  or  spores  are  still  further  specialized 
and  potentiated.  They  are  formed  by  conjugation;  that  is,  by 
the  mingling  of  the  contents  of  two  cells,  both  of  which  take  part 
in  the  formation  of  the  resulting  spore.  Fig.  77-80  exhibit  this 
conjugation  in  a  minute  silicious-coated,  one-celled  plant,  of  the 


70 


THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 


family  Desmidiacese ;  where  the  recent  dis- 
covery of  this 
process,  by  Mr. 
Ralfs,  has  con- 
firmed the  veg- 
etable character 
of  these  ambig- 
uous microscop- 
ic bodies  beyond 
all  doubt.  Also 
Figure  81  shows 
the  conjugation  of 
two  individuals  of 
Zygnema  (Spirogyra),  a  common  plant  of  our 
pools,  composed  of  single  rows  of  cells,  near- 
ly all  of  which,  in  the  figure,  are  represented 
as  taking  part  in  the  conjugation. 

103.  Plants  of  a  Tissue  of  Cells  combined  in 
one  Plane.  The  next  step  in  complexity  is 
seen  in  those  AlgaB  which  consist  of  a  few  jointed  tubes  laterally 
cohering  with  each  other  ;  or  of  numerous  cells  united  in  a  single 
plane,  as  in  the  little  Sea-weed,  Fig.  82.  This  gives  rise  to  fron- 
dose  or  leaf-like  forms.     The  name  of  Frond  is  applied  to  such 

expanded  bodies, 
which  are  neither 
leaf  nor  stem,  but 
combine  the  ap- 
pearance and  the 
office  of  both. 
Only  the  simplest 
forms,    however, 


imi 


wmn 


«»' 


mwi 


FIG.  77.  Magnified  individual  of  Closterium  acutum,  after  Ralfs.  78.  Two  individuals 
more  magnified,  in  conjugation ;  their  cells  opening  one  into  the  other,  and  the  contents  min- 
gled ;  in  79,  condensing ;  in  80,  collected  and  formed  into  a  spore. 

FIG.  81.  Magnified  view  of  two  conjugating  filaments  of  Zygnema,  showing  all  the  stages 
of  the  process  by  which  the  cells  from  different  approximated  filaments  form  each  a  corre- 
sponding protuberance,  these  come  into  contact,  the  intervening  walls  are  absorbed,  and  the 
green  contents  pass  from  one  cell  into  the  other,  condense,  acquire  an  investing  membrane, 
and  so  form  a  spore :  the  several  stages  are  shown  from  below  upwards. 

FIG.  82.  A  branch  of  Delesseria  1  LePrieurei  (from  the  Hudson  River),  enlarged  to  twice 
the  natural  size.  83.  A  small  portion  more  magnified,  to  show  the  cellular  structure.  The 
cells  have  thick  gelatinous  walls ;  those  in  the  middle  are  elongated,  those  toward  the  ma^ 
gina  rounded. 


PLANTS    WITH    A    DISTINCT    AXIS    AND    FOLIAGE. 


71 


consist  of  a  single  layer  of  cells.  Most  frondose  Sea-weeds, 
as  well  as  Lichens,  Liverworts,  &c.,  are  made  up  of  several 
such  layers.  This  is  not  the  place  to  illustrate  the  almost  end- 
less diversity  of  forms  under  which  the  frond,  or,  as  it  is  called 
in  Lichens  and  Fungi,  the  Thallus,  appears  in  these  lower  grades 
of  plants ;  nor  to  notice  their  particular  modes  of  propagation ; 
except  to  say,  in  general,  that  the  spores  are  still  nothing  but 
specialized  cells,  developed  in  some  one  of  the  ways  already 
explained.  But  we  now  begin  to  meet  with  special  organs  or 
peculiar  apparatus  in  which  the  reproductive  cells  are  formed, 
instead  of  occurring  indifferently  in  any  part. 


104.  Plants  of  a  Tissue  of  Cells  combined  into  a  solid  Axis,  or  with 
stem  and  branches.  Stem-like  solid  forms  occur,  perhaps  as  abun- 
dantly as  the  leaf-like  or  frondose,  in  the  higher  representatives  of 
the  lowest  orders  of  plants,  in  Algse,  Fungi,  and  Lichens ;  and  oc- 
casionally the  two  are  somewhat  vaguely  presented  in  the  same 
individual.  Thus,  many  of  the  larger  Sea-weeds  display  a  leaf-like 
frond  on  the  summit  of  a  solid  stalk ;  this  stem,  however,  has  once 
formed  a  part  of  the  leaf.  But  in  the  Liverwort  Family  the  dis- 
tinction is  first  clearly  exhibited,  and  in  the  true  Mosses  the  higher 
type  of  vegetation  is  fully  realized,  namely  in 

105.  Plants  with  a  Distinct  Axis  and  Foliage ;  that  is,  with  a  stem 
which  shoots  upward  from  the  soil,  or  whatever  it  is  fixed  to,  or 
creeps  on  its  surface  ;  which  grows  onward  from  its  apex,  and  is 
symmetrically  clothed  with  distinct  leaves  as  it  advances.     All 

FIG.  84.  Fruit-stalk,  with  a  portion  of  the  foliage,  of  a  Jungermannia,  magnified,  to  show 
its  entire  cellular  structure. 

FIG.  85.  One  of  the  tubular  spirally-marked  cells  from  the  fruit  of  a  Jungermannia  (a)  ;  and 
(6)  the  spiral  threads  which  result  from  its  disruption.     Some  of  the  spores  stick  to  the  tube. 

FIG.  86.    Jungermannia  Lyellii,  less  than  the  natural  size. 


72 


THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 


these  lower  vegetables  which  have  now  been  mentioned,  of  what- 
ever form,  imbibe  their  food  through  any  or  every  part  of  their 
surface,  at  least  of  the  freshly-formed  parts.  Their  roots,  when 
they  have  any,  are  usually  intended  to  fix  the  plant  to  the  rock  or 
soil,  and  not  to  draw  nourishment  from  it.  The  strong  roots  of  the 
Oar-weed^  DeviPs  Apron  (Laminaria),  and  some  other  large  Sea- 
weeds of  our  coast,  are  merely  holdfasts,  or  cords  expanding  into  a 
disc-like  surface  at  their  extremity,  which  by  their  adhesion  bind 
these  large  marine  vegetables  so  firmly  to  the  rock  that  the  force 
of  the  waves  can  seldom  carry  them  away.  Mosses  also  take  in 
their  nourishment  through  their  whole  expanded  surface,  princi- 
pally therefore  by  their  leaves :  but  the  stems  also  shoot  forth 
from  time  to  time  delicate  rootlets, 
composed  of  slender  cells  or  tubes, 
which  grow  in  a  downward  direction 
and  doubtless  perform  their  part  in 
absorption.  Although  sometimes  of 
scarcely  higher  organization  than  the 
root-hairs  which  grow  from  the  under 
side  of  a  Liverwort  (Fig.  86),  yet  they 
distinctly  introduce  the  root.  A  Moss, 
therefore,  as  respects  its  vegetation,  is 
an  ordinary  herb  in  miniature :  it  pre- 
sents an  epitome  of  the  three  universal 
Organs  of  Vegetation,  namely,  Root, 
Stem,  and  Leaves  ;  although  its  roots  are 
of  a  secondary  and  subordinate  charac- 
ter. In  the  apparatus  of  reproduction 
there  is  more  complexity,  but  no  essen- 
tial change  of  plan.  The  spores  of 
Mosses  are  formed  by  division  of  the 
contents  of  mother-cells  into  fours  (31) ; 
and  are  contained  in  Spore-cases  (or 
Sporangia)  of  peculiar  structure,  which 
are  accompanied  with  some  apparatus 
too  elaborate  to  be  described  here,  and  are  commonly  elevated, 
before  maturity,  on  a  naked  and  slender  stalk.     The  reproductive 


FIG.  87.  An  individual  of  a  Moss  (Physcomitrium  pyriforme),  enlarged  to  about  12  times 
the  natural  size.  88.  Tip  of  a  leaf,  cut  across,  much  magnified,  to  show  tliat  it  is  made  up 
(except  the  midrib)  of  a  single  layer  of  cells. 


CELLULAR  AND  VASCULAR  PLANTS.  73 

apparatus  no  longer  forms  a  part  of  the  general  tissue,  nor  is  im- 
bedded in  it,  but  special  and  altogetlier  distinct  organs  are  assigned 
to  this  office. 

106.  Thallophyles  and  Cormophytes.  It  is  convenient  to  mention 
here,  that  these  plants  of  the  lower  grades,  Algse,  Fungi,  and 
Lichens,  which  exhibit  no  proper  distinction  of  stem  and  foliage, 
are  by  some  botanists  collectively  called  Thallophytes,  that  is 
plants  formed  of  a  thallus  (103),  or  bed,  as  the  compound  word 
imports.  And  the  name  is  appropriate  for  the  greater  part  of  these 
rootless,  stemless,  and  leafless  forms  of  vegetation,  which  compose 
flat  crusts  or  plates,  like  the  common  Lichens  on  rocks,  walls,  and 
bark  ;  or  spreading  Mushrooms  ;  or  the  broad  membranous  Sea- 
weeds, such  as  the  Dulse  and  Laver  :  and  even  the  plants  of  single 
cells  or  single  rows  of  cells  are  more  commonly  aggregated  so  as 
to  make  up  a  stratum,  or  bed  of  interlaced  threads,  more  or  less 
compact  or  definite.  Such  general  names  are  seldom  character- 
istic of  every  form  they  are  meant  to  comprise.  The  contradistin- 
guishing name  of  Cormophytes  (meaning  stem-growing  plants) 
is  given  to  the  higher  forms  of  vegetation,  from  Mosses  upwards, 
because  they  develope  a  proper  stem,  usually  adorned  with  distinct 
foliage. 

107.  Cellular  and  Yascular  Plants.  While  the  Mosses  emulate 
ordinary  herbs  and  trees  in  vegetation  and  external  appearance, 
they  agree  with  the  lower  plants  in  the  simplicity  of  their  internal 
structure.  They  are  entirely  composed  of  cellular  tissue  strictly 
so  called,  chiefly  in  the  form  of  parenchyma  (51),  at  least  they 
have  no  vessels  or  ducts*  (57)  and  form  no  wood.  They,  with  all 
the  plants  below  them,  were  therefore  denominated  Cellular 
Plants  by  De  Candolle.  Those  above,  inasmuch  as  vascular  and 
woody  tissues  enter  into  their  composition,  when  they  are  herbs  as 
well  as  when  they  form  shrubs  or  trees,  he  distinguished  by  the 
general  name  of  Vascular  Plants. 

108.  The  strength  which  these  tissues  impart  —  owing  to  the fr 
toughness  and  the  close  bundles  or  masses  they  form  running 
lengthwise  through  the  stem  (53,  56)  —  enables  these  vascular 
and  woody  plants  to  attain  a  great  size  and  height ;  while  Mosses 
and  all  other  Cellular  plants  are  of  humble  size,  except  when  they 


*  The  spirally  marked  tubes  which  are  found  in  the  spore-cases  of  Liver- 
worts (Fig.  85,  a)  offer  an  exception. 
7 


74 


THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 


float  in  water,  in  which  a  few  of  the  coarser  Sea-weeds  do  indeed 
attain  a  prodigious  length  and  bulk.  The  lowest  forms  of  Vascular 
plants,  such  as  the  Club-Mosses  (Fig.  89),  are  of  humble  size,  as 
the  name  indicates,  although  the  stems  are  often  of  a  woody  tex- 
ture. Most  Ferns,  or  Brakes,  are  also  herbaceous,  or  their  persist- 
ent and  more  or  less  woody  stems  remain  underground,  in  the  form 
of  rootstocks,  or  creep  on  its  surface  (as  in  Fig.  95).  A  few  of 
them,  however,  in  the  warmer  parts  of  the  world,  rise  into  trunks, 

and  form  palm-like  trees  (Fig.  94), 
of  graceful  port,  and  sometimes  of 
great  altitude.  Thus  far,  the  roots 
are  still  of  a  secondary  character ; 
that  is,  they  spring  from  the  stem, 
wherever  it  is  in  contact  with  or 
covered  by  the  soil.  From  the 
mode  of  development  it  will  here- 
after appear  that  Ferns  and  Club- 
Mosses,  like  true  Mosses,  can  have 
no  primary  root.  The  axis,  there- 
fore, grows  from  the  apex  only, 
and  it  has  no  provision  for  increase 
in  diameter  as  it  increases  in  age. 
They  have  accordingly  received 
the  name  of  Acrogens  or  Acroge- 
Nous  Plants,  —  terms  of  Greek 
derivation,  signifying  that  they 
grow  from  the  apex  alone.  As  to 
their  fructification,  all  these  fam- 
ilies belong  to  the  great  lower  series  of 

109.  Cryptogamous  or  Flowerless  Plants.  Such  are  all  plants 
which  are  reproduced  by  spores  in  place  of  seeds.  Spores,  as  has 
been  already  shown,  are  single  specialized  cells,  which  originate 
in  some  one  of  the  ordinary  modes  of  cell-production,  and  with- 
out the  agency  of  proper  flowers.  Cryptogamous  and  Flowerless 
are  therefore  equivalent  terms;  the  former  denoting,  metaphori- 
cally, that   the    flowers   are    concealed   or   obscure.     The  great 


FIG.  89.  Lycopodium  Carolinlanum,  of  the  natural  size.  90.  A  leaf  from  the  spike  of  fruc- 
tification, with  the  spore-case  in  its  axil,  and  spores  falling  out.  91.  A  group  of  four  ^res, 
magnified.  92.  The  same  separated,  93.  A  burst  spore-case  of  Selaginella  apus,  with  its  four 
large  spores. 


PHiENOGAMOUS    OR   FLOWERING   PLANTS. 


75 


advance  made  by  Club- Mosses  and  Ferns  in  their  organs  of  veg- 
etation is  not  attended  by  any  94 
corresponding   complexity  in 
their   mode  of  reproduction. 
The    spores   of   Club-Mosses 
are  as  simple  as  those  of  true 
Mosses   themselves,  and   the 
apparatus  concerned  appears 
to   be   less    elaborate.      The 
same  may  be  said  of  Ferns. 
Even    the    tall    Tree    Ferns 
spring    from    spores    of    the 
same   simple   character,  and 
of  size  so  small  that  they  are 
separately    invisible    to    the. 
naked  eye.     It  is  worthy  of 
note,  however,  that  their  sim- 
ple spore  cases  are  borne  on 
the  leaves,  either  on  leaves  in 
their  natural  state  as  organs 
of  vegetation,  or  more  or  less 
altered  to  subserve  the  special  purpose.     For  in  like  manner,  on 
leaves  more  or  less  altered  or  specialized,  the  seeds  are  manifestly 
borne  in  the  simplest  form  of 

110.  Phscnogamous*  or  Flowering  Plants.  In  these  we  reach  at 
length  the  perfected  type,  the  highest  grade  of  vegetation.  They 
are  the  only  flower-bearing  plants,  as  their  name  indicates.  Their 
reproduction  is  effected  through  an  apparatus  essentially  different 
from  that  of  any  Cryptogamous  plants,  namely,  by  Stamens  and 
Pistils  (the  essential  organs  of  the  flower) ;  the  stamen  producing 
Pollen^  or  free  fertilizing  cells ;  the  pistil  producing  bodies  to  be 
fertilized,  called  Ovules,  and  which  after  fertilization  become  Seeds. 
While  Cryptogamous  plants  are  propagated  from  spores,  or  spe- 
cialized cells,  which  in  germination  multiply  into  other  cells,  and 

*  Sometimes  written  Phanerogamous.  Both  terms  are  made  from  the  same 
Greek  words,  and  signify,  by  a  metaphorical  expression,  the  counterpart  of 
Cryptogamous;  that  is,  that  the  essential  organs  of  the  flower  are  manifest  or 
conspicuous. 


FIG.  94.    Sketch  of  a  Tree  Fern,  Dicksonia  arborescena,  of  St.  Helena; 
Hooker.    95.  Polypodium  vulgare,  with  its  creeping  stem  or  rootstock. 


after  Dr.  J.  D. 


76         THE  GENERAL  MORPHOLOGY  OF  THE  PLANT. 

at  length  form  a  young  plant,  Phsenogamous  plants  are  propagated 
from  seeds^  which  are  more  complex  bodies,  essentially  character- 
ized by  having  already  formed  within  them,  before  they  separate 
from  the  mother  plant,  an  Embryo,  that  is  an  organized  plantlet, 
which  is  only  further  developed  in  germination. 

111.  In  the  lowest  grade  of  Phsenogamous  plants  (viz.  in  the 
Cycadacese,  and  in  the  Coniferse  or  Pine  Family),  the  flowers  are 
of  such  extreme  simplicity  that  they  consist,  some  of  a  stamen 
only,  others  of  one  or  more  naked  ovules  borne  on  the  margins  of 
an  evident  leaf,  as  in  Cycas,  or  on  the  base  or  inside  of  an  altered, 
scale-like  leaf,  as  in  the  Pine  Family.  In  the  former,  the  ovules 
answer  to  the  spore-cases  of  Ferns ;  *  in  the  latter,  to  the  spore- 
cases  of  Club-Mosses ;  thus  confirming  an  analogy  which  is  indi- 
cated by  general  aspect  between  two  of  the  higher  families  of 
Cryptogamous,  and  the  lowest  two  of  Phaenogamous  plants.  These 
are  Gymnospermous  (that  is,  naked-seeded)  Phsenogamous  plants. 
In  all  the  rest,  the  ovules  are  perfectly  inclosed  in  the  pistil,  which 
forms  a  pod  or  closed  covering  of  some  sort  for  the  seeds ;  they 
are  accordingly  distinguished  by  the  name  of  Angiospermous  (that 
is,  covered-seeded)  Phsenogamous  plants.  Their  flowers  in  the 
simplest  cases  consist,  one  sort  of  a  stamen  only,  the  other  of  a 
pistil  only ;  but  as  we  rise  in  the  scale,  these  organs  tend  to  multi- 
ply ;  to  be  combined  so  as  to  have  both  kinds  in  the  same  flower ; 
to  be  protected  or  adorned  with  a  circle  of  pecuHar  leaves  (the 
Calyx),  or  with  two  such  circles  (Calyx  and  Corolla),  of  which 
the  inner  is  commonly  more  delicate  in  texture  and  of  brighter 
color.  Thus,  the  completed  flower  exhibits  the  Organs  of  Re- 
production in  their  most  perfect  form. 

112.  The  Organs  of  Vegetation  also  exhibit  their  most  perfect 
development  in  Phsenogamous  plants.  The  three  kinds,  root,  stem, 
and  leaves,  are  almost  always  well  defined.  In  a  few  exceptional 
cases,  however,  we  have  frondose  forms ;  as  in  the  Duck-weed 
(Fig.  96),  where  stem  and  leaf  are  fused  together  into  a  green  flat 
body  which  floats  on  the  water,  emitting  roots  from  the  lower  sur- 
face and  exposing  the  upper  like  a  leaf  to  the  light.  So,  true 
leaves  scarcely  appear  in  the  Cactus  Family,  where  the  green 

*I  shall  in  another  place  have  a  better  occasion  for  indicating  an  analogy, 
hitherto  unnoticed,  between  the  typical  sporangium  of  Ferns  (viz.  that  with 
an  incomplete  vertical  ring)  and  the  anatropal  ovule. 


DEVELOPMENT    OF    THE    EMBRYO. 


77 


bark  of  the  whole  surface  takes  their  place,  although  the  points 
from  which  they  should  arise  are  distinctly  indicated ;  nor  are  they 
developed  at  all  in  the  Dodder  (135,  Fig.  122),  and  some  other 
parasitic  Flowering  plants.     In  all  Cryptogamous  plants  furnished 
with  a  distinct  axis,  or  stem,  and  leaves,  this  whole 
structure  has  to  be  formed  after  germination  (110, 
in  a  manner  to  be  hereafter  shown)  ;    and  when 
formed,  the  axis  grows  from  its  apex  only  (108),  so 
that  there  is  no  primary  root.     Phaenogamous  plants, 
on  the  contrary,  are    developed   directly  from   an 
embryo  plantlet,  an  axis  with  its  appendages,  which 
already  exists  in  the  seed,  and  which  grows  both 
ways  in  germination ;  from  one  end  to  produce  the 
stem,  and   from   the  other  to  form  the  root,  thus 
exhibiting  a  regular  opposition  of  growth  from  the 
first.     To  understand  this,  and  to  obtain  the  clear- 
est conception  of  the  plant  as  a  whole  and  of  its 
mode  of  growth,  we  should  at  the  outset  attentively  consider  the 
113.  Development  of  the  Embryo.     The  Phsenogamous  plant,  then, 
in  the  early  stage  at  which  we  begin  its  biography,  is  an  Embryo 
(Fig.  100)  contained  in  the  seed  (Fig.  99).   The  form  of  this  initial 
plantlet  varies  greatly  in  different  species.     It  is  often  an  oblong 
or  cylindrical  body,  simple  at  one  extremity,  and  nicked  or  lobed 
at  the  other,  as  in  the  case  we  have  chosen  for  illustration.     The 
undivided,  or  stem  part  is  called  the  Radicle  ;  it  is  the  rudimentary 
axis,  the  initial  stem.     The  two  lobes  into  which  the  upper  end  is 
split  are  the  Cotyledons,  or  the  undeveloped  first  pair  of  leaves, 
often  named  the  Seed-leaves.    These  are  often  so  large  as  to  make 
up  nearly  the  whole  bulk  of  the  seed,  as  in  the  pea  and  bean,  or 
the  Apple  and  Almond  (Fig.  97),  where  the 
"'^^      /""^      radicle  is  very  short  in  proportion ;    and  on 
separating  or  taking  off  one  of  them  the  mi- 
nute rudiments  of  one  or  more  additional 
leaves  may  often  be  detected  within  (Fig. 
98,  a).     The  embryo,  therefore,  consists  of 
a  short  axis  or  stem,  crowned  with  two  or 
more  undeveloped  leaves,  or,  in  other  words, 

FIG.  96,    A  Duck-weed  (Lemna  minor,  the  whole  plant),  in  flower ;  magnified. 

FIG.  97.  Embryo  (the  whole  kernel)  of  an  Almond,  the  cotyledons  slightly  separated. 
98.  The  same,  with  one  cotyledon  taken  off,  to  show  the  plumule,  or  minute  undeveloped 
leaves,  a,  between  the  two. 


97 


78 


THE    GENERAL    MORPHOLOGY    OF    THE    PLANT. 


with  a  Bud.  In  germination  the  axis  or  radicle  elongates  through- 
out, so  as  usually  to  elevate  the  budding  apex  above  the  surface  of 
the  soil,  and  its  cotyledons  expand  in  the  air  into  the  first  pair  of 
leaves ;  and  at  the  same  time  from  the  opposite  extremity  is 
formed  the  root,  which  grows  in  a  downward  direction,  so  as  to  pen- 
etrate more  and  more  into  the  soil.  The  two  extremities  of  the 
embryo  are  therefore  differently  affected  by  the  same  external  in- 
fluences, by  light  especially,  and  exhibit  exactly  opposite  tenden- 
cies. The  budding  end  invariably  rises  upwards,  as  if  it  sought 
the  light  and  air ;  the  root-end  turns  constantly  from  the  light,  and 
buries  itself  in  the  dark  and  moist  soil.  These  tendencies  are  ab- 
solute and  irreversible.  If  obstacles  intervene,  the  root  will  take  as 
nearly  a  downward,  and  the  stem  as  nearly  an  upward,  direction  as 
possible.  They  are  only  the  first  manifestation  of  an  inherent  prop- 
erty which  continues,  with  only  incidental  modifications,  through- 
out the  whole  growth  of  the  plant,  although,  like  instinct  in  the 
higher  animals,  it  is  strongest  at  the  commencement :  and  it  insures 
that  each  part  of  the  plant  shall  be  developed  in  the  medium  in 
which  it  is  designed  to  live  and  act,  —  the  root  in  the  earth,  and  the 
stem  and  leaves  in  the  air.     The  axis,  therefore,  especially  in 


plants  of  the  highest  grade,  possesses  a  kind  of  polarity  ;  it  is  com- 
posed of  two  counterpart  systems,  namely,  a  Descending  Axis  or 


FIG.  99.  A  longitudinal  section  of  a  seed,  showing  the  embryo  or  rudimentary  plant  it  con- 
tains. 100.  The  embryo  taken  from  the  seed,  and  its  rudimentary  leaves,  or  cotyledons,  a 
little  separated.  101.  The  same  in  germination,  the  cotyledons  expanding  into  the  first  pair  of 
leaves.  102-104.  The  seedling  plant  more  advanced.  (The  radicle,  or  first  joint  of  stem, 
should  have  been  drawn  more  elongated.) 


DEVELOPMENT    OF    THE    EMBRYO.  79 

root,  and  an  Ascending  Axis  or  stem.  The  point  of  union  or  base 
of  the  two  is  termed  the  croivn,  neck,  or  collar.  Both  the  root  and 
stem  branch ;  but  the  branches  are  repetitions  of  the  axis  from 
which  they  spring,  and  obey  its  laws.  The  branches  of  the  root 
tend  to  descend  ;  those  of  the  stem  tend  to  ascend. 

114.  Organs  of  Vegetation.  These  three  organs,  Stem,  Root,  and 
Leaves,  either  preexist  rudimentarily  in  the  seed,  or  appear  at  the 
first  development  of  the  embryo  in  germination.  Of, them,  vege- 
tables essentially  consist ;  for  they  are  all  that  are  requisite  to,  and 
actually  concerned  in,  their  life  and  growth.  Indeed,  the  whole  ul- 
terior evolution  of  the  plant  exhibits  only  repetitions  of  these  essen- 
tial parts,  under  more  or  less  varied  forms.  They  are,  therefore, 
properly  termed  the  Fundamental  Organs  of  plants,  or  the  Or- 
gans OF  Vegetation.  The  root  absorbs  the  crude  food  of  the 
plant  from  the  soil ;  this  is  conducted  through  the  stem  into  the 
leaves,  is  in  them  digested,  under  the  agency  of  solar  light  and 
heat;  and  the  nourishment  thus  assimilated  is  returned  into  the 
stem  and  root,  to  be  expended  in  the  formation  of  new  rootlets, 
new  branches,  and  new  leaves.  The  more  the  plant  grows,  there- 
fore, the  more  it  multiplies  its  instruments  and  means  of  growth  ; 
and  its  evolution  would  seem  to  be  limited  only  by  the  failure  of 
food,  of  a  fit  temperature,  or  other  external  circumstances. 

115.  Sooner  or  later,  however,  the  plant  changes  its  mode  of 
development,  and  bears  Flowers,  or  Organs  of  Reproduction. 
But  even  in  these,  the  philosophical  botanist  recognizes  the  stem 
and  leaves,  under  peculiar  forms,  adapted  to  special  purposes. 
And  the  object  and  consummation  of  the  flower  is  the  production 
of  seeds,  containing  an  embryo  plant  which  is  composed  of  these 
same  fundamental  organs,  and  which  in  its  development  repeats 
these  successive  steps,  to  attain  the  same  ultimate  result. 

116.  Having  briefly  traced  the  plan  and  progress  of  vegetation 
from  the  simplest  or  lowest  through  to  the  highest  or  most  elabo- 
rately perfect  grade  of  plants,  we  may,  in  the  following  chapters, 
leave  the  Cryptogamous  or  Flowerless  plants  entirely  out  of  view 
(reverting  to  them  only  to  explain  separately  the  peculiarities  of 
their  different  orders  at  the  close),  and  explain  the  phenomena, 
first  of  vegetation,  and  then  of  reproduction,  as  manifested  in  the 
higher  series  of  Phsenogamous  or  Flowering  plants.  The  simpler 
kinds  of  the  lower  series  doubtless  afford  remarkable  facilities  for 
investigating  questions  of  anatomical  structure,  and  for  ascertaining 


80  THE    ROOT. 

what  is  really  essential  to  vegetation.  But  the  general  scheme  of 
the  vegetable  kingdom,  and  the  unity  of  plan  which  runs  through 
the  manifold  diversities  it  displays,  enabling  us  to  refer  an  almost 
infinite  variety  of  details  to  a  few  general  laws,  must  be  studied  in 
the  higher  series  of  Phaenogamous  plants,  which  exhibit,  in  mani- 
fold variety  of  form,  the  completed  type  of  vegatation. 


CHAPTER    III. 

OF    THE    ROOT    OR   DESCENDING    AXIS. 

117.  The  Organs  of  Vegetation  (114)  in  Phsenogamous  plants, 
namely,  the  root,  stem,  and  leaves,  are  to  be  considered  in  succes- 
sion ;  and  it  is  on  some  accounts  most  convenient  to  begin  with 
the  root,  charged  as  it  is  with  the  earliest  office  in  the  nutrition  of 
the  vegetable,  that  of  absorbing  its  food.  According  to  our  view 
of  the  matter,  however  (113),  its  formation  does  not  precede,  but 
follows,  that  of  the  stem. 

118.  The  Primary  Root,  as  already  defined  (112-  114),  is  the  de- 
scending axis,  or  that  portion  of  the  trunk  which,  avoiding  the 
light,  grows  downwards,  fixing  the  plant  to  the  soil,  and  absorbing 
nourishment  from  it.  The  examination  of  any  ordinary  embryo 
during  germination,  such  as  that  of  the  Sugar  Maple  (Fig.  105  - 
107),  will  give  a  good  idea  of  the  formation  and  entire  peculiarities 

of  the  root.      Its  radicle    (a), 
/C^^^^^  /^^\  or  preexisting  axis,  first  of  all 

lff^^\         /V^^\  ^"^^6         grows  in  such  a  way  as  to  elon- 
\¥  m  ^\    X\>^  gate  throughout  its  whole  ex- 

o — ■'^!> Il        ^-^=— ^  tent  (thus  showing  that  it  is  not 

itts  108  itself  root,  but  the  first  joint  of 

stem) ;  this  lengthening,  while 
it  thrusts  the  root-end  downwards  ( 1 13)  a  little  deeper  into  the  soil, 
at  the  same  time  raises  the  cotyledons  (h)  to  the  surface,  and  at 
length  elevates  them  above  it,  where  they  expand  in  the  light  and 
air,  and  begin  to  perform  the  office  of  leaves  (Fig.  107).     Contem- 

FIG.  105.    An  embryo  of  Sugar  Maple,  just  unfolding  in  germination.     106.  Same,  a  little 
more  advanced ;  the  radicle,  a,  considerably  elongated. 


THE   PRIMARY    ROOT. 


81 


poraneous  with  this  elongation  of  the  radicle,  a  new  and  different 
growth  takes  place  from  its  lower 
extremity  in  a  downward  direction, 
which  forms  the  Root  (Fig.  107,  r). 
The  root  is  therefore  a  new  forma- 
tion from  the  root-end  of  the  radicle. 
It  begins  by  the  production  of  a 
quantity  of  new  cells  (by  division) 
at  the  extremity  of  the  radicle  ;  not 
on  its  surface,  however,  but  beneath 
its  thin  epidermis  and  the  superficial 
cells.  The  multiplication  of  cells  at 
this  point  proceeds  from  below  on- 
wards ;  those  behind  quickly  expand- 
ing to  their  full  size,  and  then  re- 
maining unaltered,  while  those  next 
the  apex  continue  to  multiply  by  di- 
vision. In  this  way  the  root  grows 
onward  by  continual  additions  of 
new  material  to  its  advancing  ex- 
tremity ;  lengthening  from  the  lower 
end  entirely  or  chiefly,  so  that  this 
part  of  a  growing  root  always  con- 
sists of  the  most  newly  formed  and  log 
vitally  active  tissue. 

119.  The  new  cells,  however,  do  not  occupy  the  very  point,  as 
is  commonly,  but  incorrectly,  stated.  This  is  capped,  as  it  were, 
by  an  obtusely  conical  mass  of  older  cells,  consisting  of  the  super- 
ficial tissue  of  the  end  of  the  radicle,  pushed  forward  by  the  cell- 
multiplication  that  commenced  behind  it,  as  already  mentioned 
(Fig.  108).  As  the  original  cells  of  this  apex  wear  away  or  per- 
ish, they  are  replaced  by  the  layer  beneath ;  and  so  the  advancing 
point  of  the  root  consists,  as  inspection  plainly  shows,  of  older  and 


FIG.  107.  A  germinating  embryo  of  Sugar  Maple,  still  more  advanced :  a,  the  radicle  elon- 
gated into  the  first  joint  of  stem,  bearing  the  unfolded  cotyledons  or  seed-leaves,  b,  and  between 
them  the  rudiments  of  the  next  pair  of  leaves ;  while  from  its  lower  extremity  the  root,  r,  is 
formed. 

FIG.  108.  The  lower  end  of  the  same  root,  magnified:  a,  the  place  where  growth,  through 
the  multiplication  of  cells  by  division,  is  principally  taking  place :  b,  the  original  apex  of  the 
radicle,  which  has  been  carried  onward  by  the  growth  that  has  taken  place  just  behind  it. 


I 


THE    ROOT. 


denser  tissue  than  that  behind  it.*  The  point  of  every  branch  of 
the  root  is  capped  in  the  same  way.  It  follows  that  the  so-called 
spongioles  or  spongelets  of  the  roots  have  no  existence.  Not  only 
are  there  no  such  special  organs  as  are  commonly  spoken  6f^  but 
absorption  evidently  does  not  take  place,  to  any  considerable  ex- 
tent, through  the  older  tissue  of  the  point  itself. 

120.  As  to  absorption  by  roots,  the  inspection  of  the  root  of  a 
germinating  plantlet,  or  of  any  growing  rootlet,  even  under  a  low 
magnifying  power,  shows  that  they  must  imbibe  the  moisture  that 
bathes  them,  by  endosmosis  (37),  through  the  whole  recently  formed 
surface,  and  especially  by  the  hair-like  prolongations  of  the  exterior 
layer  of  cells,  ox  fibrils^  as  they  may  be  termed,  which  are  copiously 
borne  by  all  young  roots  (Fig.  108).  Fig.  109,  110,  show  some 
of  these  root-hairs,  and  the  tissue  that  bears  them,  more  magni- 

109  fied.      These   capillary  tubes,   of 

great  tenuity  and  with  extremely 
delicate  walls,  immensely  increase 
the  surface  which  the  rootlet  ex- 
poses, and  play  a  more  important 
part  in  absorption  than  is  gener- 
ally supposed ;  for  they  appear 
to  have  attracted  little  attention. 
These  fibrils  perish  when  the 
growing  season  is  over,  or  when 
the  root  gets  a  little  older ;  at  the 
same  time,  the  external  layer  of 
cells  that  bears  them,  at  first  un- 
"°  distinguishable  from  the  parenchy- 
ma beneath,  except  perhaps  in  the  size  of  the  cells,  hardens  and 
thickens  into  a  sort  of  epidermis,  or  firmer  skin,  so  as  to  arrest  or 
greatly  restrain  the  imbibition.  This  epidermis  (69)  of  the  root 
consists  of  less  compressed  cells  than  in  parts  exposed  to  the  light, 
and  is  destitute  of  stomates  or  breathing-pores  (70). 

121.  The  growth  of  the  root  and  its  branches  keeps  pace  with  the 
development  of  the  stem.  As  the  latter  shoots  upward  and  expands 
its  leaves,  from  which  water  is  copiously  exhaled  during  vigorous 


*  It  is  a  similar  tissue  that  exfoliates  from  the  point  of  some  aquatic  (as  in 
Lerana,  Fig.  96),  and  many  aerial  roots  (as  in  Pandanus),  in  the  form  of  a 
loose  cup  or  sheath. 


THE    PRIMARY    ROOT.  83" 

vegetation^  the  former  grow  onward  and  continually  renew  the  ten- 
der, hygrometric  tissue  through  which  the  absorption,  required  to 
restore  what  is  lost  by  evaporation  or  consumed  in  growth,  is 
principally  effected.  Hence  the  danger  of  disturbing  the  active 
roots  during  the  season  of  growth.  In  early  summer,  when  the  sap 
is  rapidly  consumed  by  the  fresh  leaves,  the  rootlets  are  also  in  rap- 
id action.  The  growth  of  the  branches  and  roots  being  simultane- 
ous, while  new  branchlets  and  leaves  are  developing,  the  rootlets  are 
extending  at  a  corresponding  rate,  and  their  tender  absorbing  points 
are  most  frequently  renewed.  They  cannot  now  be  removed  from 
the  soil  without  destroying  them,  at  the  very  time  when  their  action 
is  essential  to  restore  the  liquid  which  is  exhaled  from  the  leaves. 
But  towards  the  close  of  summer,  as  the  leaves  grow  languid  and 
the  growth  of  the  season  is  attained,  the  rootlets  also  cease  to 
grow,  the  loose  tissue  of  their  extremities,  not  being  renewed,  grad- 
ually solidifies,  and  absorption  at  length  ceases.  This  indicates 
the  proper  period  for  transplanting,  namely,  in  the  autumn  sifter 
vegetation  is  suspended,  or  in  early  spring  before  it  recommences. 

122.  This  elongation  of  roots  by  their  advancing  points  alone  is 
admirably  adapted  to  the  conditions  in  which  they  are  placed. 
Growing  as  they  do  in  a  medium  of  such  unequal  resistance  as  the 
soil,  if  roots  increased  like  growing  stems,  by  the  elongation  of  the 
whole  body,  they  would  be  thrown,  whenever  the  elongating  force 
was  insufficient  to  overcome  the  resista-nce,  into  knotted  or  con- 
torted shapes,  very  ill  adapted  for  the  free  transmission  of  fluid. 
But,  lengthening  only  at  their  farthest  extremity,  they  insinuate 
themselves  with  great  facility  into  the  crevices  or  yielding  parts  of 
the  soil,  and  afterwards  by  their  expansion  in  diameter  enlarge  the 
cavity  ;  or,  when  arrested  by  insuperable  obstacles,  their  advan- 
cing points  follow  the  surface  of  the  opposing  body  until  they  reach 
a  softer  medium.  In  this  manner,  too,  they  readily  extend  from 
place  to  place,  as  the  nourishment  in  their  immediate  vicinity  is 
consumed.  Hence,  also,  may  be  derived  a  simple  explanation  of 
the  fact,  that  roots  extend  most  rapidly  and  widely  in  the  direction 
of  the  most  favorable  soil,  without  supposing  any  prescience  on  the 
part  of  the  vegetable,  as  some  have  imagined. 

123.  The  advancing  extremity  of  the  root  consists  of  parenchy- 
ma alone ;  but  bundles  of  vessels  and  woody  tissue  appear  in  the 
forming  root,  soon  after  their  appearance  in  the  primordial  stem 
above  :  these  form  a  central  woody  or  fibrous  portion,  which  con- 


%4 


THE    ROOT. 


tinues  to  descend  (by  the  transformation  of  a  portion  of  the  nas- 
cent tissue)  as  the  growing  apex  advances  ;  sometimes,  aUhough 
not  usually,  inclosing  a  distinct  pith,  as  the  wood  of  the  stem 
does.  The  surrounding  parenchymatous  portion  becomes  the  bark 
of  the  root.  Increase  in  diameter  takes  place  in  the  same  way  as 
in  the  stem.     (Chap.  IV.  Sect.  IV.) 

124.  We  have  taken  the  root  of  the  seedling  as  an  example  and 
epitome  of  that  of  the  whole  herb  or  tree  ;  as  we  rightly  may ;  for 
in  its  whole  development  the  root  produces  no  other  parts-;  it 
bears  nothing  but  naked  branches,  which  spring  from  different 
portions  of  the  surface  of  the  main  root,  nearly  as  this  sprung  from 
the  radicle,  and  exactly  imitate  its  growth.  They  and  their  rami- 
fications are  mere  repetitions  of  the  original  descending  axis,  serv- 
ing to  multiply  the  amount  of  absorbing  surface.  The  branches  of 
the  root,  moreover,  shoot  forth  without  apparent  order ;  or  at  least 
in  no  order  like  that  of  the  branches  of  the  stem,  which  have  a 
symmetrical  arrangement,  dependent,  as  we  shall  see,  upon  the 
arrangement  of  the  leaves. 

125.  To  the  general  statement  that  roots  give  birth  to  no  other 
organs,  there  is  this  abnormal,  but  by  no  means  unusual  exception, 
that  of  producing  buds  and  therefore  sending  up  leafy  branches. 
Although  not  naturally  furnished  with  buds,  like  the  stem,  yet, 
under  certain  circumstances,  those  of  many  trees  and  shrubs,  and 
of  several  herbs,  have  the  power  of  producing  them  abundantly. 
Thus,  when  the  trunk  of  a  young  Apple-tree  or  Poplar  is  cut  off 
near  the  ground,  while  the  roots  are  vigorous  and  full  of  sap, 
those  which  spread  just  beneath  the  surface  produce  buds,  and 
give  rise  to  a  multitude  of  young  shoots.  The  roots  of  the  Ma- 
dura, or  Osage  Orange,  habitually  give  rise  to  buds  and  branches. 
Such  buds  are  said  to  be  irregular,  or  adventitious.  This  power, 
however,  roots  share  with  every  part  of  the  vegetable  that  abounds 
with  parenchyma :  even  leaves  are  known  to  produce  adventitious 
buds. 

.  126.  The  root  has  been  illustrated  from  the  highest  class  of 
Phsenogamous  plants;  in  which  the  original  root,  or  downward 
prolongation  of  the  axis,  continues  to  grow,  at  least  for  a  consider- 
able time,  and  becomes  a  tap-root.,  or  main  trunk,  from  which 
branches  of  larger  or  smaller  size  emanate.  Often,  however,  this 
main  root  early  perishes  or  ceases  to  grow,  and  the  branches  take 
its  place.     In  some  plants  of  the  highest  class  (in  the  Gourd  Fam- 


ANNUAL,    BIENNIAL,   AND   PERENNIAL    ROOTS.  85 

ily,  for  example),  and  in  nearly  the  whole  great  class  to  which 
Grasses,  Lilies,  and  Palms  belong,  there  is  no  one  main  trunk  or 
primary  root  from  which  the  rest  proceed  ;  but  several  roots  spring 
forth  almost  simultaneously  from  the  radicle  in  germination,  and 
form  a  cluster  of  fibres,  of  nearly  equal  size  (Fig.  111).  Such 
plants  scarcely  exhibit  that  distinct  opposition  of  growth  in  the  first 
instance,  already  mentioned  as  one  characteristic  of  Phsenogamous 
vegetation.  Most  Phsenogamous  plants  likewise  shoot  forth  secon- 
dary roots  from  the  stem  itself,  the  only  kind  produced  by  Cryp- 
togamous  plants.  To  these  we  must  revert,  after  having  consid- 
ered some  diversities  connected  with  the  duration  and  form  of 
roots,  and  an  important  subsidiary  purpose  which  they  often  sub- 
serve. 

127.  Annual  Roots  are  those  of  a  plant  which  springs  from  the 
seed,  flowers,  and  dies  the  same  year  or  season.  Such  plants  al- 
ways have  jibrous  roots,  composed  of  numerous  slender  branches, 
fibres,  or  rootlets,  proceeding  laterally  from  the  main  or  taprroot, 
which  is  very  little  enlarged,  as  in  Mustard,  &c. ;  or  else  the  whole 
root  divides  at  once  into  such  fibrous  branches,  as  in  Barley  (Fig. 
Ill)  and  all  annual  Grasses.  These  multiplied  rootlets  are  well 
adapted  for  absorption  from  the  soil,  but  for  that  alone.  The  food 
which  the  roots  of  such  a  plant  absorbs,  after  being  digested  and 
elaborated  in  its  leaves,  is  all  expended  in  the  production  of  new 
leafy  branches,  and  at  length  of  flowers.  The  flowering  process 
and  the  maturing  of  the  fruit  exhaust  the  vegetable  greatly  (in  a 
manner  hereafter  to  be  explained),  consuming  all  the  nourishing 
material  which  it  contains,  or  storing  it  up  in  the  fruit  or  seed  for 
its  offspring ;  and  having  no  stock  accumulated  in  the  root  or  else- 
where to  sustain  this  draught,  the  plant  perishes  at  the  close  of  the 
season,  or  whenever  it  has  fully  gone  to  seed. 

128.  Biennial  Roots  are  those  of  plants  which  do  not  blossom 
until  the  second  season,  after  which  they  perish  like  annuals.  In 
these  the  root  serves  as  a  reservoir  of  nourishing,  assimilated  mat- 
ter (27,  79) ;  its  cells  therefore  become  gorged  with  starch  (81), 
vegetable  jelly  (83),  sugar  (84),  &c.  Such  thickened  roots  are 
said  to  be  fleshy^  and  receive  different  names  according  to  the 
shapes  they  assume.  When  the  accumulation  takes  place  in  the 
main  trunk  or  tap-root,  it  becomes  conical,  as  in  the  Carrot,  Fig. 
1 12,  when  it  tapers  regularly  from  the  base  or  crown  to  the  apex ; 
it  is  fusiform  or  spindle-shaped  when  it  tapers  upwards  as  well  as 

8 


THE    ROOT. 


downwards,  as  in  the  Radish,  Fig.  113;  or  napiform  or  turnip- 
shaped,  when  much  swollen  at  the  base,  so  as  to  become  broader 
than  long.  If  some  of  the  branches  or  fibres  are  thickened,  instead 
of  the  main  axis,  the  root  is  said  to  be  fasciculated  or  clustered, 
as  in  Fig.  114  ;  or  tuberiferous  or  tuberous,  when  they  assume  the 
form  of  rounded  knobs,  as  in  Fig.  115;  or  palmate,  when  the 
knobs  are  branched,  as  in  Fig.  116.  These  must  not  be  con- 
founded with  tubers,  such  as  potatoes,  which  are  forms  of  stems. 
Most  of  these  are  biennial.  Such  plants  (of  which  the  Radish, 
Carrot,  Beet,  and  Turnip,  among  our  esculents,  are  familiar  exam- 
ples) neither  flower  the  first  season,  nor  even  expend  in  the  pro- 
duction of  stems  and  branches  much  of  the  nourishment  they  gen- 
erate ;  but,  forming  a  large  tuft  of  leaves  at  the  very  surface  of 
the  ground,  they  accumulate  in  the  root  nearly  the  whole  sum- 
mer's supply  of  nourishment.  When  vegetation  is  resumed  the 
following  spring,  they  make  a  strong  and  rapid  growth,  shooting 
forth  a  large  stem,  and  bearing  flowers,  fruit,  and  seed,  almost 
wholly  at  the  expense  of  the  accumulation  of  the  previous  year ; 
this  store  is  soon  consumed,  therefore;  and  the  plant,  meanwhile 
neglecting  to  form  new  roots,  perishes  from  exhaustion. 


129.  Perennial  Roots.  A  third  class  of  herbs,  and  all  woody 
plants,  do  not  so  absolutely  depend  upon  the  stock  of  the  previous 
season,  but  annually  produce  new  roots  and  form  new  accumula- 
tions ;  sometimes  in  separate  portions  of  the  root,  as  in  the  Dahlia 


FIG.  111-116.    Different  kinds  of  roota. 


SECONDARY    ROOTS.  87 

or  the  Orchis  (Fig.  115),  where,  while  one  or  more  of  such  reser- 
voirs is  exhausted  each  year,  others  are  providently  formed  for 
the  next  year's  sustenance  ;  and  so  on  from  year  to  year ;  a  por- 
tion annually  perishing,  but  the  individual  plant  surviving  indefi- 
nitely. More  commonly,  the  whole  body  and  main  branches  of 
the  root  are  somewhat  thickened  ;  or  portions  of  the  stem  may 
subserve  this  purpose,  as  in  all  tuberous  herbs ;  or  the  nourishing 
matter  may  be  widely  distributed  through  the  trunk,  as  in  shrubs 
and  trees.  These  are  some  of  the  modifications  in  this  respect  of 
perennial  plants,  which  survive,  or  at  least  their  roots,  and  blossom 
from  year  to  year  indefinitely. 

130.  Secondary  Roots.  (Also  called  Adventitious  Roots.)  Thus 
far,  the  primitive  root,  that  which  originated  from  the  base  of  the 
embryo  in  germination,  with  its  ramifications,  has  alone  been  con- 
sidered. But  roots  habitually  spring  from  any  part  of  a  growing 
stem  that  lies  on  the  ground,  or  is  buried  beneath  its  surface,  so  as 
to  provide  the  moisture  and  darkness  they  require ;  for  such  roots 
obey  the  ordinary  tendency  of  the  organ,  avoiding  the  light,  and 
seeking  to  bury  themselves  in  the  soil.  Most  creeping  plants  pro- 
duce them  at  every  joint ;  and  most  branches,  when  bent  to  the 
ground  and  covered  with  earth,  will  strike  root.  So,  often,  will 
separate  pieces  of  young  stems,  if  due  care  be  taken ;  as  when 
plants  are  propagated  by  cuttings.  Stems  commonly  do  not  strike 
root,  except  when  in  contact  with  the  ground.  To  this,  however, 
there  are  various  exceptions  ;  as  in  the  case  of 

131.  Aerial  Roots.  Some  woody  vines  climb  by  such  rootlets ; 
as  the  Ivy,  our  own  Poison  Ivy  (Rhus  Toxicodendron),  and  the 
Bignonia  or  Trumpet-Creeper,  which  in  this  way  reach  the  sum- 
mit of  high  trees.  Such  plants  derive  their  nourishment  from  their 
ordinary  roots  imbedded  in  the  soil ;  their  copious  aerial  rootlets 
merely  serving  for  mechanical  support.  Other  plants  produce 
true  aerial  roots,  which,  emitted  from  the  stem  in  the  open  air, 
descend  to  the  ground  and  establish  themselves  in  the  soil.  This 
may  be  observed,  on  a  small  scale,  in  the  stems  of  Indian  Corn, 
where  the  lower  joints  often  produce  roots  which  grow  to  the 
length  of  several  inches  before  they  reach  the  soil.  More  striking 
cases  of  the  kind  abound  in  those  tropical  regions  where  the  sultry 
air,  saturated  with  moisture  for  a  large  part  of  the  year,  favors  the 
utmost  luxuriance  of  vegetation.  The  Pandanus  or  Screw-Pine  (a 
Palm-like  tree,  often  cultivated  in  our  conservatories)   affords  a 


88 


THE    ROOT. 


welt-known  instance.     The  strong  roots,  emitted  in  the  open  air 
from  the  lower  part  of  the  trunk,  soon  reach  the  soil,  as  is  shown 

in  Fig.  117,  giving 
the  tree  the  appear- 
ance of  having  been 
partially  raised  out 
of  the  ground.  The 
famous  Banyan-tree 
(Fig.  119)  affords  a 
still  more  striking 
illustration.  Here 
the  aerial  rootlets 
strike  from  the  hor- 
izontal branches  of 
the  tree,  often  at  a 
great  height,  and 
swing  free  in  the 
air,  like  pendent 
cords ;  but  they  fi- 
nally reach  and  es- 
tablish themselves 
in  the  ground,  where 
they  increase  in  di- 
ameter  and   form   numerous  accessory  trunks,  surrounding   the 


FIG.  117.    The  Pandanus,  or  Screw-Pine ;  with,  118,  a  Mangrove-tree  (Rhizophora  Mangle). 
FIG.  119.    The  Banyan-tree,  or  Indian  Fig  (Ficus  Indica). 


EPIPHYTES    OR    AIR-PLANTS. 


89 


original  bole  and  supporting  the  wide-spread  canopy  of  branches 
and  foliage.  Very  similar  is  the  economy  of  the  Mangrove  (Fig. 
118),  which  inhabits  muddy  sea-shores  throughout  the  tropics,  and 
even  occurs  sparingly  on  the  coast  of  Florida  and  Louisiana.  Its 
aerial  roots  spring  both  from  the  main  trunk,  as  in  the  Pandanus, 
and  from  the  branchlets,  as  in  the  Banyan.  Moreover,  this  ten- 
dency to  shoot  in  the  air  is  shown  even  in  the  embryo,  which  be- 
gins to  germinate  while  the  pod  is  yet  attached  to  the  parent 
branch  ;  the  radicle,  or  root-end  of  the  embryo,  elongating  into  a 
slender  thread,  which  often  reaches  the  ground  from  the  height  of 
many  yards,  before  the  pod  is  detached.  In  this  manner  the  Man- 
grove forms  those  impenetrable  maritime  thickets  which  abound 
on  low,  muddy  shores,  within  the  tropics. 


132.  Epiphytes,  or  Air-plants,  exhibit  a  further  peculiarity.  Their 
roots  not  only  strike  in  the  free  air,  but  throughout  their  life  have 
no  connection  with  the  soil.    They  generally  grow  upon  the  trunks 

FIG.  120.    Oncidium  Papilio,  and,  121,  Comparettia  rosea;   two  epiphytes  of  the  Orchis 
Family ;  showing  the  mode  in  which  these  Air-plants  grow. 


90  THE    ROOT. 

and  branches  of  trees ;  their  roots  merely  adhering  to  the  bark  to 
fix  the  plant  in  its  position,  or  else  hanging  loose  in  the  air,  from 
which  such  plants  draw  all  their  nourishment.  Of  this  kind  are  a 
large  portion  of  the  gorgeous  Orchidaceous  plants  of  very  warm 
and  humid  climes,  which  are  so  much  prized  in  hot-houses,  and 
which,  in  their  flowers  as  well  as  their  general  aspect,  exhibit  such 
fantastic  and  infinitely  varied  forms.  Some  of  the  flowers  resem- 
ble butterflies,  or  strange  insects,  in  shape  as  well  as  in  gaudy  col- 
oring ;  such,  for  example,  as  the  Oncidium  Papilio  (Fig.  120), 
which  we  have  selected  for  one  of  our  illustrations.  To  another 
family  of  Epiphytic  plants  belongs  the  Tillandsia,  or  Long  Moss, 
which,  pendent  in  long  and  gray  tangled  clusters  or  festoons  from 
the  branches  of  the  Live-Oak  or  Long-leaved  Pine,  gives  such  a 
peculiar  and  sombre  aspect  to  the  forests  of  the  warmer  portions 
of  our  Southern  States.  They  are  called  Air-plants,  in  allusion  to 
the  source  of  their  nourishment ;  and  Epiphytes,  from  their  grow- 
ing upon  other  plants,  and  in  contradistinction  to 

133.  Parasites,  that  not  only  grow  upon  other  vegetables,  but  live 
at  their  expense  ;  which  Epiphytes  do  not.  Parasitic  plants  may 
be  divided  into  two  sorts,  viz. :  —  1st,  those  that  have  green  foli- 
age, and  2d,  those  that  are  destitute  of  green  foliage.  They  may 
vary  also  in  the  degree  of  parasitism ;  the  greater  number  being 
absolutely  dependent  upon  the  foster  plant  for  nourishment,  while 
a  few,  such  as  the  Cursed  Fig  (Clusia  rosea)  of  tropical  America, 
often  take  root  in  the  soil,  and  thence  derive  a  part,  or  sometimes 
the  whole,  of  their  support.     This  occurs  only  in 

134.  Green  Parasites,  or  those  furnished  with  green  foliage,  or 
proper  digestive  organs  of  their  own.  These  strike  their  roots 
through  the  bark  g.nd  directly  into  the  new  wood  of  the  foster 
plant ;  whence  they  can  draw  little  except  the  ascending,  mostly 
crude  sap  (79),  which  they  have  to  assimilate  in  their  own  green 
leaves.  The  Mistletoe  is  the  most  familiar  example  of  this  class. 
It  is  always  completely  parasitic,  being  at  no  period  connected 
with  the  earth  ;  but  the  seed  germinates  upon  the  trunk  or  branch 
of  the  tree  where  it  happens  to  fall,  and  its  nascent  root,  or  rather 
the  woody  mass  that  it  produces  in  place  of  the  root,  penetrates 
the  bark  of  the  foster  stem,  and  forms  as  close  a  junction,  ap- 
parently, with  its  young  wood  as  that  of  a  natural  branch.  Some 
species  of  Mistletoe,  or  of  the  same  family,  however,  display  no 
proper  green  foliage,  but  are  of  a  yellow  or  brown  hue.     On  the 


PARASITIC    PLANTS. 


91 


other  hand,  imperfect  root-parasites  with  green  foliage  have  re- 
cently been  detected  in  more  than  one  tribe  of  plants ;  *  thus  ex- 
hibiting intermediate  states  between  the  Green  and  the 

135.  Pale  or  Colored  Parasites^  that  is,  of  other  colors  than 
green ;  such  as  Beech-drops,  Orobanche,  &c.  These  strike  their 
roots,  or  sucker-shaped  discs,  into  the  bark,  mostly  that  of  the  root, 
of  other  plants,  and  thence  draw 
their  food  from  the  sap  already  elab- 
orated (79).  They  have  according- 
ly no  occasion  for  digestive  organs 
of  their  own,  and  are  in  fact  always 
destitute  of  green  foliage.  In  some 
cases  of  the  kind,  as  in  the  Dodder 
(Fig.  122- 124),  the  seeds  germinate 
in  the  earth,  from  which  the  primi- 
tive root  derives  its  nourishment  in 
the  ordinary  manner ;  but  when  the 
slender  twining  stem  reaches  the 
surrounding  herbage,  it  gives  out 
aerial  roots,  which  attach  themselves 
firmly  to  the  surface  of  the  support- 
ing plant,  penetrate  its  epidermis, 
and  feed  upon  its  juices  ;  while  the 
original  root  and  base  of  the  stem  perish,  and  the  plant  has  no 
longer  any  connection  with  the  soil.  Thus  stealing  its  nourish- 
ment ready  prepared,  it  requires  no  proper  digestive  organs  of  its 


*  In  England  a  Thesium  was  discovered  by  Mr.  Mitten  to  attach  its  roots 
parasitically,  by  suckers,  to  the  roots  of  adjacent  herbs.  (It  would  be  inter- 
esting to  know  if  this  is  the  case  with  our  Comandra.)  Then  Decaisne,  recol- 
lecting that  Rhinanthaceous  plants  generally,  all  of  which  blacken  more  or 
less  in  drying,  were  known  to  be  uncultivable,  and  have  the  reputation,  in 
France  and  elsewhere,  of  being  injurious  to  cereal  and  other  plants  in  their 
vicinity,  was  led  to  the  discovery  that  plants  of  Rhinanthus,  Melampyrum, 
and  of  the  allied  genera,  attached  themselves  by  numerous  suckers  on  their 
roots  to  the  roots  of  Grasses,  shrubby  plants,  and  even  of  trees,  among  which 
they  grow.  Our  handsome  species  of  Gerardia  are  equally  uncultivable, 
doubtless  on  account  of  this  partial  parasitism. 

FIG.  122.  The  common  Dodder  of  the  Northern  States  (Cuscuta  Gronovii),  of  the  natural 
size,  parasitic  upon  the  stem  of  an  herb:  the  uncoiled  portion  at  the  lower  end  shows  the  mode 
of  its  attachment.  123.  The  coiled  embryo  taken  from  the  seed,  moderately  magnified.  124.  The 
same  in  germination;  the  lower  end  elongating  into  a  root;  the  upper  into  a  thread-like  leaf- 
less slem. 


92  THE    ROOT. 

own,  and,  consequently,  does  not  produce  leaves.  This  economy- 
is,  as  it  were,  foreshadowed  in  the  embryo  of  the  Dodder,  which 
is  a  slender  thread  spirally  coiled  in  the  seed  (Fig.  123,  124),  and 
which  presents  no  vestige  of  cotyledons  or  seed-leaves.  A  spe- 
cies of  Dodder  infests  and  greatly  injures  flax  in  Europe,  and 
sometimes  makes  its  appearance  in  our  own  flax-fields,  having 
been  introduced  with  the  imported  seed.  Some  species  make 
great  havoc  in  the  clover- fields  of  the  Old  World. 

136.  Such  parasites  do  not  live  upon  all  plants  indiscriminately, 
but  only  upon  those  whose  elaborated  juices  furnish  a  propitious 
nourishment.  Some  of  them  are  restricted,  or  nearly  so,  to  a  par- 
ticular species ;  others  show  little  preference,  or  are  found  indif- 
ferently upon  several  species  of  different  families.  Their  seeds, 
in  some  cases,  it  is  said,  will  germinate  only  when  in  contact  with 
the  stem  or  root  of  the  species  upon  which  they  are  destined  to 
live.  Having  no  need  of  foliage,  such  plants  may  be  reduced  to  a 
stalk  with  a  single  flower  or  cluster  of  flowers,  as  in  the  different 
kinds  of  Beech-drops,*  the  Cytinus,  which  is  parasitic  on  the  Cistus 
of  the  South  of  Europe,  &c.  They  may  even  be  reduced  to  a 
single  flower  directly  parasitic  on  the  bark  of  the  foster  plant, 
without  the  intervention  of  any  manifest  stem.  A  truly  wonderful 
instance  of  this  kind  is  furnished  by  that  vegetable  Titan,  the  Raf- 
flesia  Arnoldi  of  Sumatra  (Fig.  125).     The  flower  which  was  first 


discovered  grew  upon  the  stem  of  a  kind  of  grape-vine  ;  it  meas- 
ured nine  feet  in  circumference,  and  weighed  fifteen  pounds  !  Its 
color  is  light  orange,  mottled  with  yellowish-white. 

*  See  family  Orobanchacete,  in  the  second  part  of  this  work. 

FIG.  125.    Rafflesia  Arnoldi ;  an  expanded  flower,  and  a  bud,  directly  parasitic  on  the  etem 
of  a  vine :  reduced  to  the  scale  of  half  an  inch  to  a  foot. 


THE    STEM.  93 

137.  Among  Cryptogamous  plants,  numerous  Fungi  are  para- 
sitic upon  living,  especially  upon  languishing  vegetables ;  others 
infest  living  animals ;  the  rest  feed  on  dead  or  decaying  vegeta- 
ble or  animal  matters  :  all  are  destitute  of  chlorophyll  (87),  or  any 
thing  like  green  foliage.  It  is  not  improbable  that  our  Monotropa, 
or  Indian  Pipe,  a  pallid  and  fungus-like  Phsenogamous  plant,  draws 
its  nourishment,  at  least  in  great  part,  from  the  decaying  leaves 
among  which  it  grows. 


CHAPTER    IV. 

OF    THI^    STEM,    OR    ASCENDING    AXIS. 

Sect.  I.    Its  General  Characteristics  and  Mode  of  Growth. 

138.  Besides  the  direction  of  its  growth,  the  descending  axis  or 
root  we  have  found  to  be  characterized  by  producing  nothing  ex- 
cept naked  branches  or  subdivisions,  and  these  in  no  definite  order  ; 
by  their  continued  extension  through  new  formation  at  the  extrem- 
ity only,  and  in  an  uninterrupted  manner,  so  as  to  give  rise  to  no 
joints  or  nodes,  and  consequently  to  bear  no  leaves  (141) ;  by  the 
absence  of  stomates  in  its  epidermis  (which,  however,  is  the  case 
in  all  parts  developed  under  ground) ;  and  commonly  by  having 
no  pith  in  the  centre,  or  only  a  minute  pith  at  the  base,  where  it 
joins  the  stem.  The  latter  organ  differs  in  nearly  all  these  par- 
ticulars. 

139.  The  Stem  is  the  ascending  axis,  or  that  portion  of  the  trunk 
which  in  the  embryo  grows  in  an  opposite  direction  from  the  root, 
seeking  the  light,  and  exposing  itself  as  much  as  possible  to  the 
air.  All  Phsenogamous  plants  (110)  possess  stems.  In  those 
which  are  said  to  be  acaulescent,  or  stemless,  it  is  either  very  short, 
or  concealed  beneath  the  ground.  Although  the  stem  always  takes 
an  ascending  direction  at  the  commencement  of  its  growth,  it  does 
not  uniformly  retain  it ;  but  sometimes  trails  along  the  surface  of 
the  ground,  or  burrows  beneath  it,  sending  up  branches,  flower- 
stalks,  or  leaves  into  the  air.  'The  common  idea,  therefore,  that 
all  the  subterranean  portion  of  a  plant  belongs  to  the  root,  is  by  no 
means  correct. 


94  THE    STEM. 

140.  The  root  gives  birth  to  no  other  organs,  but  itself  directly 
performs  those  functions  which  pertain  to  the  relations  of  the  veg- 
etable with  the  soil ;  —  its  branches  bind  the  plant  to  the  earth  ;  its 
newly  formed  extremities,  or  fresh  rootlets,  with  the  capillary  fibrils 
they  bear,  imbibe  nourishment  from  it.  But  the  aerial  functions 
of  vegetation  are  chiefly  carried  on,  not  so  much  by  the  stem  it- 
self as  by  a  distinct  set  of  organs  which  it  bears,  namely,  the 
leaves.  Hence,  the  production  of  leaves  is  one  of  the  characteris- 
tics of  the  stem.  These  are  produced  only  at  certain  definite 
and  symmetrically  arranged  points,  called 

141.  Nodes,  literally  knots^  so  named  because  the  tissues  are  here 
condensed,  interlaced,  or  interrupted,  more  or  less,  as  is  conspicu- 
ously seen  in  the  Bamboo,  in  a  stalk  of  Indian  Corn,  or  of  any 
other  Grass.  Here  each  node  forms  a  complete  indurated  ring, 
because  the  leaf  arises  from  the  whole  circumference  of  the  stem 
at  that  place.  When  the  base  of  the  leaf  or  leaf-stalk  occupies 
only  a  part  of  the  circumference,  the  nodes  are  not  so  distinctly 
marked,  except  by  the  leaves  they  bear,  or  by  the  scars  left  by 
their  fall  (Fig.  127,  130).  When  distinct  they  are  often  called 
joints,  and  sometimes,  indeed,  the  stem  is  nciuoWy  jointed^  or  cirtiC' 
ulated,  at  these  points ;  but  commonly  there  is  no  tendency  to 
separate  there.  Each  node  bears  either  a  single  leaf,  or  two 
placed  on  opposite  sides  of  the  stem  (Fig.  104),  or  three  or  more, 
placed  in  a  ring  (in  botanical  language,  a  whorl  or  verticil)  around 
the  stem.  The  naked  portions  or  spaces  that  intervene  between 
the  nodes  are  termed 

142.  Illternodes.  The  undeveloped  stem  is,  in  fact,  made  up  of 
a  certain  number  of  these  leaf-bearing  points,  separated  by  short 
intervals ;  and  its  growth  consists,  primarily,  in  the  elongation  of 
these  internodes  (much  after  the  mode  in  which  the  joints  of  a 
pocket-telescope  are  drawn  out  one  after  the  other),  so  as  to  sep- 
arate the  nodes  to  a  greater  or  less  distance  from  each  other,  and 
allow  the  leaves  to  expand. 

143.  This  brings  to  view  the  leading  peculiarity  of  the  stem, 
namely,  that  it  is  formed  of  a  succession  of  similar  parts,  developed 
one  upon  the  summit  of  another,  each  with  its  own  independent 
growth  :  each  developing  internode,  moreover,  lengthens  through- 
out its  whole  body,  unlike  the  root,  which  elongates  continuously 
from  its  extremity  alone.  The  nodes  or  the  leaves  they  bear  are 
first  formed,  in  close  contiguity  with  the   preceding ;    then   the 


NODES  AND  INTERNODES. BUDS.  95 

internodes  appear,  and  by  their  elongation  separate  them,  and  so 
carry  upward  the  stem.  To  have  a  good  idea  of  this,  we  have 
only  to  observe  the  gradual  evolution  of  a  germinating  plant,  where 
each  internode  developes  nearly  to  its  full  length,  and  expands  the 
leaf  or  pair  of  leaves  it  bears,  before  the  elongation  of  the  succeed- 
ing one  commences.  The  radicle,  or  internode  which  preexists 
in  the  embryo  (118)  elongates,  and  raises  the  seed-leaves  into  the 
air  (Fig.  107) ;  they  expand  and  elaborate  the  material  for  the 
next  joint,  the  leaves  of  which  in  turn  prepare  the  material  for  the 
third  (Fig.  102-104),  and  so  on.  The  internode  lengthens  princi- 
pally by  the  elongation  of,  its  already  formed  cells,  particularly  in 
its  lower  part,  which  continues  to  grow  after  the  upper  portion  has 
finished. 

144.  BudSi  The  apex  of  the  stem,  accordingly,  at  least  of  every 
stem  capable  of  further  terminal  growth,  is  always  crowned  with 
an  undeveloped  portion,  the  rudiments  of  parts  similar  to  those 
already  unfolded,  that  is,  with  a  Bud  (113).  The  embryo  itself 
may  be  rightly  viewed  as  the  fundamental  bud  borne  on  the  apex 
of  the  radicle  or  original  internode,  from  which  the  whole  plant  is 
developed ;  just  as  an  ordinary  bud  of  a  tree  or  shrub  developes 
to  form  a  year's  growth.  Except  that,  in  the  latter  case,  the  differ- 
ent steps  follow  each  other  more  closely ;  for  the  bud  usually 
has  a  considerable  number  of  parts  ready  formed  in  miniature  be- 
fore it  begins  to  grow,  and  has  a  full  store  of  assimilated  sap  accu- 
mulated in  the  parent  stem  to  feed  upon.  Such  buds,  which 
appear  at  the  apex  of  a  stem  when  it  has  completed  its  growth  for 
the  season,  often  exhibit  the  whole  plan  and  amount  of  the  next 
year's  growth ;  the  nodes,  and  even  the  leaves  they  bear,  being 
already  formed,  and  only  requiring  the  elongation  of  the  inter- 
nodes for  their  full  expansion.  The  structure  is  shown  in  the  an- 
nexed diagram  (Fig.  126),  which  represents  the  vertical  section  of  a 
bud  (like  that  which  crowns  the  stem  in  Fig.  127),  as  it  appears  in 
early  spring.  As  the  bud  is  supplied  by  the  stem  on  which  it  rests 
with  nourishment  sufficient  for  its  whole  development,  it  elongates 
rapidly ;  and  although  the  growth  commences  with  the  lowest 
internode,  and  follows  the  same  course  as  in  the  seedling,  yet  the 
second,  third,  and  fourth  internodes,  &;c.,  have  begun  to  lengthen 
long  before  the  first  has  attained  its  full  growth ;.  as  is  attempted 
to  be  shown  by  the  diagram.  Fig.  128.  The  stem  thus  continued 
from  a  terminal  bud  is,  if  it  survive,  again  terminated  with  a  sim- 


96 


THE    STEM. 


ilar  bud  at  the  close  of  the  season,  which  in  its  development  re- 
peats the  same  process. 

145.  These  yearly   growths,  in    trees  with  well-formed  Scaly 

Buds,  such  as  the  Magnolia 
(Fig.  130),  the  Horsechestnut 
(Fig.  127),  &c.,  are  plainly 
marked  by  the  assemblage  of 
scars  or  rings  on  the  bark  (a), 
which  mark  the  places  where 
the  bud-scales  were  attached. 
The  reason  why  these,  and 
the  leaf-scars,  are  obliterated 
after  a  few  years  will  appear 
when  the  increase  of  the  stem 
in  diameter  is  considered. 
The  bud-scales  themselves, 
which  so  closely  overlie  each 
other  and  protect  the  tender 
parts  within  against  injury 
from  moisture  and  sudden 
changes  of  temperature  dur- 
ing the  dormant  state,*  are 
only  a  special  modification 
of  leaves,  developed  in  this 
shape  at  a  time  when  the  internodes  have  ceased  to  elongate ; 
so  that  the  space  between  each  ring  in  the  figure  just  referred  to 
represents  an  undeveloped  internode.  Such  a  stem  displays  alter- 
nately two  modes  of  growth.  First,  the  internodes  elongate  and 
interspace  a  succession  of  leaves,  making  the  proper  vegetation  of 


*  The  more  effectually  to  ward  off  moisture,  they  are  commonly  covered 
with  a  waxy,  resinous,  or  balsamic  exudation  (as  in  the  Poplar  especially), 
impervious  to  rain,  but  which  is  melted  by  the  heat  of  the  sun  when  it  stimu- 
lates the  bud  into  growth.  To  guard  against  sudden  changes  of  temperature, 
they  are  often  lined,  or  the  rudimentary  leaves  within  are  invested,  with  non- 
conducting down  or  wool. 

^  FIG.  126.    Diagram  of  a  longitudinal  section  of  a  bud,  such  as  that  of  the  Horsechestnut, 

FIG.  127.    A  year's  growth  of  a  Horsechestnut  branch,  crowned  with  a  terminal  bud :  a, 
scars  left  by  the  bud-scales  of  the  previous  year  :  b,  scars  left  by  the  fallen  leaf-stalks  :  c,  axil- 
lary buds. 
FIG.  123,    Diagram  to  illustrate  the  development  of  the  bud  in  Fig,  126,  127. 
FIG.  129.    Branch  and  buds  (all  axillary)  of  the  Lilac. 


BUDS. 


97 


the  season.  Then  a  series  of  leaves  form  as  bud-scales,  with  inter- 
nodes  incapable  of  extension,  and  within  them  the  rudiments  of  the 
next  year's  vegetation  are  prepared,  to 
be  developed  as  before,  after  a  season 
of  repose.  As  might  be  expected, 
therefore,  such  scaly  (or  perulate) 
huds  belong  to  trees  and  shrubs  of 
countries  which  have  a  winter;  and 
are  not  met  with,  at  least  distinctly,  in 
those  of  the  tropics ;  where,  as  there 
is  no  danger  of  injury  from  cold,  the 
first  parts  that  appear  in  the  bud  are 
ordinary  leaves.  Indeed,  very  many 
trees  and  shrubs  of  cold  climates  bear 
naked  huds^  as  the  Locust,  Honey  Lo- 
cust, Ailanthus,  &c.,  or  buds  with  little 
scaly  covering,  as  in  the  Kentucky 
Coffee-tree,  the  Papaw,  &c.  But  in 
these  cases  the  bud  scarcely  projects 
so  as  to  be  visible  externally  until  it 
begins  to  develope  in  the  spring.  In 
Viburnum,  some  species,  such  as  V. 
Opulus,  &c.,  have  proper  scaly  buds, 
while  in  V.  lantanoides,  V.  nudum, 
&c.,  they  are  entirely  naked. 

146.  The  bud,  it  is  evident,  is  noth- 
ing more  than  the  first  stage  in  the 
development  of  a  stemr  (or  branch), 
the  axis  still  so  short  that  the  scales 
without  and  the  rudimentary  leaves 
within  cover  or  overlap  one  another. 
Tlie  various  ways  in  which  these  parts 
are  packed  in  the  bud  will  be  consid- 
ered under  another  head  (Vernation, 
257).  That  the  scales  of  the  bud 
are  of  the  same  general  nature  as  leaves  is  evident,  not  only  from 


FIG.  130.  Branch  of  Magnolia  Umbrella,  of  the  natural  size,  crowned  with  the  terminal  bud ; 
and  below  exhibiting  the  large,  rounded  leaf-scars,  and  the  annular  scars  left  by  the  fall  of  the 
bud-scales,  of  the  previous  season.  131.  A  detached  scale  from  a  similar  bud  ;  its  thickened 
axis  is  the  base  of  a  leafstalk ;  the  membranous  sides  consist  of  the  pair  of  stipules. 

9 


98  THE    STEM. 

their  position,  but  from  their  gradual  transition  into  ordinary  leaves 
in  many  cases.  This  is  well  seen  in  the  expanding  buds  of  the 
Lilac,  Hickory,  Horsechestnut,  and  especially  of  the  Buckeye. 
The  scales  represent,  sometimes  the  blade  of  the  leaf,  as  in  the 
Lilac ;  but  more  commonly  the  dilated  base  of  the  leaf-stalk, 
as  is  evident  in  the  Balsam  Poplar,  Butternut,  and  Hickory ;  or 
their  stipules  (259),  either  combined  with  this  base,  as  in  the  Mag- 
nolia (Fig.  131),  or  alone,  as  in  the  Tulip-tree.  Scales  passing 
into  ordinary  leaves  are  abundantly  obvious  on  the  turions,  or 
subterranean  budding  shoots,  of  numerous  perennial  herbs. 

147.  By  the  development  of  the  preexisting  bud  in  the  embryo, 
the  original  stem  is  produced  ;  and  it  may  be  continued  from  year 
to  year  by  the  continued  evolution  of  a  terminal  hud.  Growing  in 
this  way  only,  the  stem  would  of  course  remain  simple  or  un- 
branched  ;  as  is  the  case  with  many  during  the  first  year,  and  whh 
others,  such  as  most  Palms  (Fig.  166)  and  Reeds  throughout  their 
whole  existence.  But  more  commonly  branches  appear,  even 
during  the  first  year's  growth. 

Sect.  II.     Ramification. 

148.  Branches  spring  from  lateral  or  axillary  huds.  These  are 
new  undeveloped  axes  or  growing  points,  which  habitually  appear, 
or  at  least  may  appear,  one  (or  occasionally  two  or  three)  in  the 
axil  of  each  leaf,  that  is,  in  the  upper  angle  which  the  leaf  forn\s 
with  the  stem.  (See  Fig.  127,  c,  where  the  point  at  which  the 
fallen  leaves  were  attached  is  marked  by  the  broad  scar,  h,  just  be- 
low the  bud.)  The  axillary  bud  is  at  first  a  little  cellular  nucleus 
on  the  surface  of  the  wood,  at  the  end  of  one  of  the  cellular  lines 
that  form  the  silver-grain  (196),  and  underneath  the  bark,  through 
which  it  pushes  as  it  grows,  and  shapes  itself  into  a  rudimen- 
tary axis,  covered  with  the  little  appendages  which  become  scales 
or  leaves.  When  these  buds  grow,  they  give  rise  to  Branches  ; 
which  are  repetitions,  as  it  were,  of  the  main  stem,  growing  just 
as  that  did  from  the  seed  ;  excepting  merely,  that,  while  that  was 
implanted  in  the  ground,  these  proceed  from  the  parent  stem. 
The  branches  thus  produced  are  in  turn  provided  with  similar 
buds  in  the  axils  of  their  leaves,  which  have  the  same  relation  to 
the  primary  branch  that  it  has  to  the  main  stem,  and  are  capable 
of  developing  into  branches  of  a  third  order,  and  so  on  indefinite- 


RAMIFICATION.  99 

ly,  producing  the  whole  ramification  of  the  plant.  The  whole  is 
merely  a  series  of  repetitions,  from  new  starting-points,  of  what 
took  place  in  the  evolution  of  the  first  axis,  preexistent  in  the  seed. 
In  the  seed,  therefore,  or  rather  in  the  embryo  it  contains,  we  have 
the  expression,  in  a  condensed  form,  of  the  whole  being  of  the 
plant.  The  latest  ramifications,  or  twigs,  are  termed  Branch- 
lets. 

149.  The  arrangement  of  axillary  buds  depends  upon  that  of 
the  leaves.  When  the  leaves  are  opposite  (that  is,  two  on  each 
node,  placed  on  opposite  sides  of  the  stem),  the  buds  in  their  axils 
are  consequently  opposite;  as  in  the  Maple,  Horsechestnut  (Fig. 
127),  Lilac  (Fig.  129),  &c.  When  the  leaves  are  alternate,  or  one 
upon  each  node,  as  in  the  Apple,  Poplar,  Oak,  Magnolia  (Fig. 
130),  &c.,  the  buds  implicitly  follow  the  same  arrangement. 
Branches,  therefore,  being  developed  buds,  their  arrangement  is 
not  left  to  chance,  but  is  predetermined,  symmetrical,  and  gov- 
erned by  fixed  laws.  When  the  leaves  are  alternate,  the  branches 
will  be  alternate  :  when  the  leaves  are  opposite,  and  the  huds  de- 
velope  regularly,  the  branches  will  be  opposite.  In  other  words, 
if  a  bud  in  the  axil  of  each  leaf  is  developed  into  a  branch,  the 
relative  situation  of  the  branches  will  be  the  same  as  that  of  the 
leaves. 

150.  But  the  regular  symmetry  of  the  ramification  is  often  ac- 
cidentally interfered  with  by  various  causes,  especially  by  the  non- 
development  of  many  huds.  As  the  original  embryo  plant  remains 
for  a  time  latent  in  the  seed,  growing  only  when  a  conjunction  of 
favorable  circumstances  calls  its  life  into  action,  so  also  many  of 
the  buds  of  a  shrub  or  tree  may  remain  latent  for  an  indefinite 
time,  without  losing  their  power  of  growth.  In  our  trees,  most  of 
the  lateral  buds  generally  remain  dormant  for  the  first  season  : 
they  appear  in  the  axils  of  the  leaves  early  in  summer,  but  do  not 
grow  into  branches  until  the  following  spring ;  and  even  then  only 
a  part  of  them  usually  grow.  Sometimes  the  non-development  or 
suppression  occurs  without  appreciable  order  ;  but  it  often  follows 
a  nearly  uniform  rule  in  each  species.  Thus,  when  the  leaves  are 
opposite,  there  are  usually  three  buds  at  the  apex  of  a  branch  ; 
namely,  the  terminal,  and  one  in  the  axil  of  each  leaf;  but  it  sel- 
dom happens  that  all  three  grow  at  the  same  time.  Sometimes 
the  terminal  bud  continues  the  branch,  the  two  lateral  generally 
remaining  latent,  as  in  the  Horsechestnut ;  sometimes  the  termi- 


100  THE    STEM. 

nal  one  is  regularly  suppressed,  and  the  lateral  grow,  when  the 
stem  annually  becomes  forked,  as  happens  in  the  Lilac  (Fig.  129). 

151.  The  undeveloped  buds  do  not  necessarily  perish,  but  are 
ready  to  be  called  into  action  in  case  the  others  are  checked. 
When  the  terminal  buds  are  destroyed,  some  of  the  lateral,  that 
would  else  remain  dormant,  develope  in  their  stead,  incited  by  the 
abundance  of  nourishment,  which  the  former  would  have  monop- 
olized. In  this  manner  our  trees  are  soon  reclothed  with  verdure, 
after  their  tender  foliage  and  branches  have  been  killed  by  a  late 
vernal  frost,  or  other  injury.  The  buds  may  remain  latent  even 
for  years,  and  become  covered  with  wood.  The  trunk  of  a  tree, 
therefore,  always  contains  an  immense  number ;  some  of  which, 
after  a  long  period,  may  force  their  way  through  the  wood  to  the 
surface,  and  break  forth  into  branches  ;  especially  when  the  tree  is 
pollarded^  or  its  leading  branches  injured. 

152.  Adventitious  Buds.  But  many  such  branches  have  an  ahnor- 
mal  origin,  from  irregular  or  adventitious  buds^  like  those  pro- 
duced by  roots  under  similar  circumstances  (125).  Such  buds  are 
still  more  readily  produced  on  woody  stems,  when  surcharged 
with  sap,  as  we  constantly  observe  on  pollard  Willows  and  Lom- 
bardy  Poplars.  Indeed,  in  several  instances,  buds  are  known  to 
arise  even  from  the  surface  or  margins  of  leaves,  as  in  Bryo- 
phyllum,  which  derives  its  name  from  this  unusual  circumstance ; 
and  the  gardener  produces  them  from  root-cuttings  or  leaf-cuttings 
of  certain  plants,  which  he  propagates  in  this  way.  Adventitious 
buds  originate  in  the  parenchyma,  some  cells  of  which  are  incited 
to  take  an  independent  development.  In  trees,  they  form  on  the 
surface  of  the  wood,  at  the  ends  of  the  lines  of  the  silver-grain 
(medullary  rays,  191,  196).  They  are  especially  liable  to  spring 
from  the  new  cellular  tissue  that  forms  at  the  growing  season 
between  the  wood  and  bark  when  the  trunk  is  wounded  or  cut  off. 
Thus  the  predestined  symmetry  of  the  branches  is  obscured  or 
interfered  with  in  two  distinct  ways ;  first,  by  the  failure  of  a  part 
of  the  regular  buds  to  develope  ;  and  secondly,  by  the  irregular  or 
casual  development  of  buds  from  other  parts  than  the  axils  of  the 
leaves :  to  which  we  may  add,  that  great  numbers  of  branches 
perish  and  fall  away  after  they  have  begur^^  to  grow  or  have  at- 
tained considerable  size.  There  is  still  another  source  of  irregu- 
larity, namely,  in  the  production  of 

153.  Accessory  Buds,     These  are,  as  it  were,  multiplications  of 


ADVENTITIOUS    AND   ACCESSORY   BUDS. 


101 


the  regular  axillary  bud,  giving  rise  to  two,  three,  or  more,  instead 
of  one ;  in  some  cases  situated  one  above  another,  in  others  side 
by  side.  In  the  latter  case,  which  occurs  occasionally  in  the 
Hawthorn,  in  certain  Willows,  in  the 
Maples  (Fig.  132),  &c.,  the  axillary  bud 
seems  to  divide  into  three,  or  itself  give 
rise  to  a  lateral  bud  on  each  side,  as 
soon  as  or  before  it  penetrates  the  bark. 
In  the  Tartarean  Honeysuckle  as  many 
as  half  a  dozen  buds  are  developed  in- 
dependently in  each  axil,  one  above 
another,  the  lower  being  successively 
the  stronger  and  earlier  produced,  and 
the  one  immediately  in  the  axil,  there- 
fore, grows  in  preference ;  but  when 
some  of  the  others  grow,  superposed 
accessory  branches  appear.  It  is  much 
the  same  in  Aristolochia  Sipho,  ex- 
cept that  the  uppermost  bud  is  there 
strongest.  So  it  is  in  the  Butternut 
(Fig.  133),  where  the  true  axillary  bud 
is  minute  and  usually  remains  latent, 
while  the  accessory  ones  are  considera- 
bly remote,  and  the  uppermost,  which 
is  much  the  strongest,  is  far  out  of  the 
axil ;  usually  this  alone  developes,  and        132  133 

gives  rise  to  an  extra-axillary  branch. 

154.  The  stems  of  those  Cryptogamous  plants  that  possess  a 
proper  trunk  (the  Horsetails  or  Scouring  Rushes  excepted)  do  not 
branchy  by  the  development  of  axillary  or  any  kind  of  lateral  buds 
implanted  on  its  surface  ;  but  they  often  fork  at  the  apex,  by  the 
division  of  the  terminal  bud.  Their  ramification,  like  their  whole 
growth,  is  merely  acrogenous,  or  from  the  apex  (108). 

155.  Excurrent  aud  Deliquescent  Stems.  Sometimes  the  primary 
axis  is  prolonged  without  interruption,  by  the  continued  evolution 
of  the  terminal  bud,  even  through  the  whole  life  of  a  tree  (unless 
accidentally  destroyed),  forming  an  undivided  main  trunk,  from 


FIG.  132.    Branch  of  Red  Maple,  with  triple  axillary  buds,  placed  side  by  side. 
FIG.  133.    Piece  of  a  branch  of  the  Butlermit,  with  accessory  buds  placed  one  above  an- 
other :  a,  the  leaf-scar :  6,  proper  axillary  bud :  c,  d,  accessory  buds. 

9* 


102 


THE    STEM. 


which  lateral  branches  proceed ;  as  in  most  Fir-trees.  Such  a 
trunk  is  said  to  be  excurrent.  In  other  cases  the  main  stem  is  ar- 
rested, sooner  or  later,  either  by  flowering,  by  the  failure  of  the 
terminal  bud,  or  the  more  vigorous  development  of  some  of  the 
lateral  buds^  and  thus  the  trunk  is  lost  in  the  branches,  or  is  deli- 
quescent, as  in  most  of  our  deciduous-leaved  trees.  The  first  nat- 
urally gives  rise  to  conical  or  spire-shaped  trees ;  the  second,  to 
rounded  or  spreading  forms.  As  stems  extend  upward  and  evolve 
new  branches,  those  near  the  base,  being  overshadowed,  are  apt 
to  perish,  and  thus  the  trunk  becomes  naked  below.  This  is 
well  seen  in  the  excurrent  trunks  of  Firs  and  Pines,  which,  when 
grown  in  forest,  seem  to  have  been  branchless  for  a  great  height. 
But  the  knots  in  the  centre  of  the  trunk  are  the  bases  of  branch- 
es, which  have  long  since  perished,  and  have  been  covered  with  a 
great  number  of  annual  layers  of  wood,  forming  the  clear-stuff  of 
the  trunk. 

156.  Definite  and  Indefinite  Annual  Growth  of  Branches.  In  the  lar- 
ger number  of  our  trees  and  shrubs,  especially  those  with  scaly 
buds,  the  whole  year's  growth  is  either  already  laid  down  rudi- 
mentally  in  the  bud  (144),  or  else  is  early  formed;  and  the  de- 
velopment is  completed  long  before  the  end  of  summer,  and 
crowned  with  a  vigorous  terminal  bud  (as  in  the  Horsechestnut, 
Fig.  127,  Magnolia,  Fig.  130,  &c.),  or  with  the  uppermost  axillary, 
as  in  the  Lilac  (Fig.  129).  ^y\c\i- definite  shoots  do  not  die  down 
at  all  the  following  winter,  but  grow  on  directly,  the  next  spring, 
from  the  terminal  or  some  of  the  upper  axillary  buds,  which  are 
generally  more  vigorous  than  those  lower  down.  In  others,  on 
the  contrary,  the  branches  grow  onward  indefinitely  through  the 
whole  summer,  or  until  arrested  by  the  cold  of  autumn  :  they  ma- 
ture no  terminal  or  upper  axillary  buds  ;  or  at  least  the  lower  and 
older  axillary  buds  are  more  vigorous,  and  alone  develope  into 
branches  the  next  spring;  the  later-formed  upper  portion  most 
commonly  perishing  from  the  apex  downward  for  a  certain  length 
in  the  winter.  The  Rose  and  Raspberry,  and  among  trees  the  Su- 
mac and  Honey  Locust,  are  good  illustrations  of  this  sort ;  which, 
however,  runs  into  the  other  mode  through  various  gradations. 
Perennial  herbs  grow  after  the  latter  mode,  their  stems  dying 
down  to  or  beneath  the  surface  of  the  ground,  where  the  persistent 
base  is  charged  with  vigorous  buds,  well  protected  by  the  ground, 
for  the  next  year's  vegetation. 


KINDS    OF    STEM    AND    BRANCHES.  103 

157.  Propagation  from  Buds.  Buds,  being,  as  it  were,  new  indi- 
viduals springing  from  the  original  stem,  may  be  removed  and 
attached  to  other  parts  of  the  parent  trunk,  or  to  that  of  another 
individual  of  the  same,  or  even  of  a  different,  but  nearly  related 
species,  where  they  will  grow  equally  well.  This  is  directly  ac- 
complished in  the  operation  of  hudding.  In  ingrafting,  the  bud  is 
transferred,  along  with  a  portion  of  the  shoot  on  which  it  grew. 
Moreover,  as  the  cut  end  of  such  shoots,  when  buried  in  moist  and 
warm  soil,  will  commonly,  under  due  care,  send  out  adventitious 
roots,  they  may  be  made  to  grow  independently,  drawing  their 
nourishment  immediately  from  the  soil,  instead  of  indirectly 
through  the  parent  trunk.  This  is  done  in  the  propagation  of 
plants  by  cuttings.  The  great  importance  of  these  horticultural 
operations  rests  chiefly  on  the  well-known  fact,  that  buds  propa- 
gate individual  peculiarities^  or  varieties,  which  are  commonly 
lost  in  raising  plants  from  the  seed. 

Sect.  III.     The  Kinds  of  Stem  and  Branches. 

158.  On  the  size  and  duration  of  the  stem  the  oldest  and  most 
obvious  division  of  plants  is  founded,  namely,  into  Herbs,  Shrubs, 
and  Trees. 

159.  Herbs  are  plants  in  which  the  stem  does  not  become  woody 
and  persistent,  but  dies  annually  or  after  flowering,  down  to  the 
ground  at  least.  The  difference  between  annual,  hiennial,  and 
j)erennial  herbs  has  already  been  pointed  out  (127-130).  The 
same  species  is  so  often  either  annual  or  biennial,  according  to  cir- 
cumstances or  the  mode  of  management,  that  it  is  convenient  to 
have  a  common  name  for  plants  that  flower  and'  fruit  but  once,  at 
whatever  period,  and  then  perish :  such  De  Candolle  accordingly 
designated  as  Monocarpic  plants ;  while  to  perennials,  whether 
herbaceom  or  woody,  large  or  small,  he  applied  the  counterpart 
name  of  Polycarpic  plants,  signifying  that  they  bear  fruit  more 
than  once,  or  an  indefinite  number  of  times.  Between  herbs  and 
shrubs  there  are  the  intermediate  gradations  of 

160.  Ullderslirubs,  or  suffruticose  plants,  which  are  woody  plants 
of  humble  stature,  their  stems  rising  little  above  the  surface.  If 
less  decidedly  woody,  they  are  suffrutescent. 

161.  Shrubs  are  woody  plants,  with  stems  branched  from  or 
near  the  ground,  and  less  than  five  times  the  height  of  a  man.    Be- 


104  THE    STEM. 

tween  shrubs  and  trees  there  is  every  intermediate  gradation.  A 
shrub  which  approaches  a  tree  in  size,  or  imitates  it  in  port,  is  said 
to  be  arborescent. 

162.  Trees  are  woody  plants  with  single  trunks,  which  attain  at 
least  five  times  the  human  stature. 

163.  A  Culm  is  a  name  apphed  to  the  peculiar  jointed  stem  of 
Grasses  and  Sedges,  whether  herbaceous,  as  in  most  Grasses,  or 
woody  or  arborescent,  as  in  the  Bamboo. 

164.  A  Caildex  is  a  name  usually  applied  to  a  Palm-stem  (Fig. 
166),  to  that  of  a  Tree  Fern  (Fig.  94),  and  to  any  persistent, 
erect,  or  ascending,  root-like  forms  of  main  stems.  It  is  some- 
times nearly  synonymous  with  the  rhizoma  (174). 

165.  Those  stems  which  are  too  weak  to  stand  upright,  but  re- 
cline on  the  ground,  rising,  however,  towards  the  extremity,  are 
said  to  be  decumbent :  if  they  rise  obliquely  from  near  the  base, 
they  are  said  to  be  ascending.  When  they  trail  flat  on  the  ground, 
they  are  procumbent.,  prostrate.,  or  running  ;  and  when  such  stems 
strike  root  from  their  lower  surface,  as  they  are  apt  to  do,  they  are 
said  to  be  creeping^  or  repent. 

166.  They  are  called  Climbers.,  when  they  cling  to  neighbouring 
objects  for  support ;  whether  by  tendrils,  as  the  Vine  and  Passion- 
flower; by  their  leaf-stalks,  as  the  Virgin's  Bower  (Clematis),  or 
by  aerial  rootlets,  as  the  Poison  Oak  (Rhus) ;  and  Tiviners.,  or 
twining  plants,  when  they  rise,  like  the  Convolvulus,  by  coiling 
spirally  around  stems  or  other  bodies  within  their  reach.  Other 
modifications  of  the  stem  or  branches  have  received  particular 
names,  some  of  which  merit  notice  from  having  undoubtedly  sug- 
gested several  important  operations  in  horticulture. 

167.  A  Stolon  is  a  form  of  branch  which  curves  or  falls  down  to 
the  ground,  where,  favored  by  shade  and  moisture,  it  strikes  root, 
and  then  forms  an  ascending  stem,  which  is  thus  capable  of  draw- 
ing its  nourishment  directly  from  the  soil.  The  portion  which 
connects  it  with  the  parent  stem  at  length  perishing,  the  new  indi- 
vidual acquires  an  entirely  separate  existence.  The  Currant, 
Gooseberry,  &c.,  multiply  in  this  way,  and  doubtless  suggested  to 
the  gardener  the  operation  of  layering  ;  in  which  he  not  only  takes 
advantage  of  and  accelerates  the  attempts  of  nature,  but  incites 
their  production  in  species  which  do  not  ordinarily  multiply  in  this 
manner.  Plants  which  spread  or  multiply  by  this  natural  layering 
are  said  to  be  stoloniferous. 


KINDS    OF    STEM    AND    BRANCHES. 


105 


168.  A  Sucker  is  a  branch  of  subterranean  origin,  which,  after 
running  horizontally  and  emitting  roots  in  its  course,  at  length,  fol- 
lowing its  natural  tendency,  rises  out  of  the  ground  and  forms  an 
erect  stem,  which  soon  becomes  an  independent  plant.  The  Rose, 
the  Raspberry,  and  the  Mint,  afford  familiar  illustrations,  as  well 
as  many  other  species  which  shoot  up  stems  "  from  the  root,"  as  is 
generally  thought,  but  really  from  subterranean  branches.  By 
cutting  off  the  connection  with  the  original  root,  the  gardener  prop- 
agates such  plants  hy  division.  Plants  which  produce  suckers  are 
said  to  be  surculose. 

169.  A  Runner,  of  which  the  Strawberry  furnishes  the  most  fa- 
miliar example,  is  a  prostrate,  slender  branch,  sent  off  from  the 
base  of  the  parent  stem,  which  strikes  root  at  its  apex,  and  pro- 
duces a  tuft  of  leaves ;  thus  giving  rise  to  an  independent  plant 
capable  of  extending  itself  in  the  same  manner.  Branches  of  this 
sort  are  termed  Jiagelliform. 

170.  An  Offset  is  a  similar,  but  short,  prostrate  branch,  with  a 
tuft  of  leaves  at  the  end,  which, 
resting  on  the  ground,  there  takes 
root,  and  at  length  becomes  inde- 
pendent ;  as  in  the  Houseleek. 

171.  A  Tendril  is  commonly  a 
thread-like,  leafless  branch,  capa- 
ble of  coiling  spirally,  by  which 
climbing  plants  attach  themselves 
to  surrounding  bodies ;  as  in  the 
Grape-vine  (Fig.  134).  But  some- 
times tendrils  belong  to  the  leaves, 
as  in  the  Pea  ;  when  they  are  slen- 
der prolongations  of  the  leaf-stalk. 
Stems  or  stalks  which  bear  tendrils 
are  cirrhose,  or  cirrhiferous. 

172.  A  Spine  or  Thorn  is  an  im- 
perfectly developed,  indurated,  leaf- 
less branch  of  a  woody  plant,  atten- 
uated to  a  sharp  rigid  point.  Their 
nature  is  manifest  in  the  Hawthorn 
(Fig.  136),  not  only  by  their  position  in  the  axil  of  a  leaf,  but  often 


FIG.  134.    End  of  a  shoot  of  the  Grape-vine,  showing  the  tendrila. 


106 


THE    STEM. 


by  their  bearing  Imperfect  leaves  themselves.     In  the  Sloe,  Pear, 

&c.,  many  of  the  feebler 
branches  become  spinose 
or  spines  cent  at  the  apex, 
tapering  off  gradually  in- 
to a  rigid  leafless  point. 
These  are  less  liable  to 
appear  on  the  cultivated 
tree,  when  duly  cared 
for,  such  branches  being 
thrown  into  more  vigorous 
growth.  In  the  Hawthorn, 
the  spines  spring  from  this 
peculiar  growth  of  the  main 
axillary  bud,  but  it  bears 
an  accessory  bud  (153)  on 
each  side,  one  or  the  other 
of  which  grows  into  an 
ordinary  branch.  In  the 
Honey  Locust,  it  is  the 
uppermost  of  several  ac- 
cessory buds,  placed  far 
above  the  axil,  that  de- 
velopes  into  the  thorn 
(Fig.  135).  In  this  tree 
the  spine  itself  branches,  and  sometimes  becomes  extremely  com- 
pound. Sometimes  the  stipules  of  the  leaves  develope  into  spines, 
as  in  the  Prickly  Ash. 

173.  The  Subterranean  Modifications  of  the  Stem  are  scarcely  less 

numerous  and  diverse  than  the  aerial ;  but  they  may  all  be  reduced 
to  a  few  principal  types.  They  are  perfectly  distinguishable  from 
roots  by  producing  regular  buds,  or  by  being  marked  with  scars, 
which  indicate  the  former  insertion  of  leaves,  or  furnished  with 
scales,  which  are  the  rudiments  or  vestiges  of  leaves.  All  the 
scaly  roots  of  the  older  botanists  are  therefore  forms  of  the  stem  or 
branches,  with  which  they  accord  in  every  essential  respect ;  they 

FIG.  135.  Branching  thorn  of  the  Honey  Locust  (Gleditschia),  an  indurated  branch  devel- 
oped from  an  accessory  bud  produced  above  the  axil,  a,  Three  buds  under  the  base  of  tlie  leaf- 
stalk, brought  to  view  in  a  section  of  the  stem  and  leaf-stalk  below. 

FIG.  136.  Thorn  of  the  Cockspur  Thorn,  developed  from  the  central  of  three  axillary  buds ; 
one  of  the  lateral  ones  is  seen  at  its  base. 


ITS    SUBTERRANEAN    MODIFICATIONS. 


107 


grow,  also,  in  the  opposite  direction  from  roots.  So,  likewise,  what 
were  called  (as  they  are  still  popularly  considered)  creeping  roots 
are  really  subterranean  branches ;  such  as  those  of  the  Mint,  and 
of  most  Sedges  and  Grasses.  Some  of  these,  such  as  the  Carex 
areilaria  (Fig.  137)  of  Europe,  render  important  service  in  binding 
the  shifting  sands  of  the  sea-shore.  Others,  like  the  Couch-Grass, 
are  often  very  troublesome  to  the  agriculturist,  who  finds  it  next  to 
impossible  to  destroy  them  by  the  ordinary  operations  of  husbandry ; 
for,  being  furnished  with  buds  and  roots  at  every  node,  which  are 
extremely  tenacious  of  life,  when  torn  in  pieces  by  the  plough, 
each  fragment  is  only  placed  in  the  more  favorable  condition  for 
becoming  an  independent  plant.  The  Nut-Grass  (Cyperus  Hydra), 
an  equally  troublesome  pest  to  the  planters  of  Carolina  and  Geor- 
gia, is  similarly  constituted  ;  and  besides,  the  interminable  subter- 
ranean branches  bear  tubers,  or  reservoirs  of  nutritive  matter,  in 
their  course,  which  have  still  greater  powers  of  vitality,  as  they 
contain  a  copious  store  of  food  for  the  development  of  the  buds 
they  bear.     The  name  of 


174.  Rhizoma  or  RootstOCk  is  applied  in  a  general  way  to  all 
these  perennial,  horizontally  elongated,  and  more  or  less  subterra- 
nean root-like  forms  of  the  stem  ;  and  more  particularly  to  those 
which  are  thickened  by  the  accumulation  of  nutritive  matter  in 


FIG.  137.    Creeping  subterranean  stem  of  Carex  arenaria. 

FIG.  13S.  Rhizoma  of  Dipliylleia  cymosa,  showing  six  years'  growth,  and  a  bud  for  the 
seventh  :  a,  the  bud  :  b,  base  of  the  stalk  of  the  current  year:  c,  scar  left  by  the  decay  of  the 
annual  stalk  of  the  year  before;  and  beyond  are  the  scars  of  previous  years. 


108  THE    STEM. 

their  tissue  (chiefly  in  the  form  of  starch,  81),  such  as  the  so- 
called  roots  of  Ginger,  of  the  Iris  or  Flower-de-luce,  of  the  Cala- 
mus or  Sweet  Flag,  and  of  the  Blood-root.  They  grow  after  the 
manner  of  ordinary  stems,  advancing  from  year  to  year  by  the  an- 
nual development  of  a  bud  at  the  apex,  and  emitting  roots  from  the 
under  side  or  the  whole  surface  ;  thus  established,  the  most  ancient 
portions  die  and  decay,  as  corresponding  additions  are  made  to  the 
opposite  growing  extremity.  Each  year's  growth  is  marked  m  the 
rootstock  of  the  Iris,  &c.,  by  a  set  of  annular  leaf-scars,  left  by  the 
decay  of  the  foliage  of  that  year.  In  the  Solomon's  Seal  and  the 
Diphylleia  (Fig.  138)  it  is  more  indelibly  recorded  by  the  series  of 
broad  and  rounded  scars  on  the  upper  surface,  not  unlike  the  im- 
pression of  a  seal  (whence  the  popular  name  of  Solomon's  Seal), 
which  is  left  by  the  separation  in  autumn  of  the  herbaceous  stalk 
of  the  season.  The  rootstock  of  Diphylleia  is  merely  a  string  of 
such  thickened  and  extremely  abbreviated  axes,  formed  by  the 
annual  development  of  a  bud  which,  without  elongation,  sends  up 
at  once  the  single  herbaceous  stalk  that  bears  the  foliage  and  flow- 
ers. In  our  common  Dentaria  or  Toothwort,  and  in  Hydrophyllum, 
the  base  of  this  annual  stalk  or  of  the  leaf-stalks  partakes  in  the 
thickening  and  persists  as  a  part  of  the  rhizoma,  in  the  form  of 
fleshy  scales  or  tooth-shaped  processes.  In  other  scaly  rootstocks, 
these  persistent  bases  of  the  leaves  are  thin  and  more  like  bud- 
scales,  and  slowly  decay  after  a  year  or  two.  All  such  markings 
are  vestiges  of  leaves,  .&c.,  and  indicate  the  nodes  :  they  show 
that  the  body  that  bears  them  belongs  to  the  stem  ;  not  to  the  root, 
which  is  wholly  leafless.  Rootstocks  branch,  like  other  stems,  by 
the  development  of  lateral  buds  from  the  axils  of  their  scales  or 
leaves.  Thickened  rootstocks  serve  as  a  reservoir  of  nourishing 
matter,  for  the  maintenance  of  the  annual  growth,  in  the  same 
manner  as  thickened  roots  (128).  When  such  subterranean  stems 
are  thickened  interruptedly,  they  produce 

175.  A  Tuber.  This  is  usually  formed  by  the  enlargement  of 
the  apex,  or  growing  bud,  of  a  subterranean  branch,  the  elongation 
of  which  is  arrested,  and  the  whole  excessively  thickened,  by  the 
deposition  of  starch,  &c.,  in  its  tissue.  This  accumulation  serves 
for  the  nourishment  of  the  buds  (eyes)  which  it  involves,  when 
they  develope  the  following  year.  The  common  Potato  oflers  the 
most  familiar  example  ;  and  it  is  very  evident  on  inspection  of  the 
growing  plant,  that  the  tubers  belong  to  branches,  and  not  to  the 


ITS    SUBTERRANEAN    MODIFICATIONS. 


109 


roots.  The  nature  of  the  Potato  is  also  well  shown  by  an  acci- 
dental case  (Fig,  140),  in  which  some  of  the  buds  or  branches 
above  ground  showed  a  strong  tendency  to  develope  in  the  form  of 
tubers.  By  heaping  the  soil  around  the  stems,  the  number  of  tu- 
beriferous  branches  is  increased.  The  Jerusalem  Artichoke  affords 
a  good  illustration  of  the  tuber  (Fig.  139).  A  tuber  of  a  rounded 
form,  and  with  few  buds,  is  nearly  the  same  as 


176.  A  Corm  (Cormus),  or  Solid  Bulb.  This  is  a  fleshy  sub- 
terranean stem,  of  a  round  or  oval  figure,  and  a  uniform,  com- 
pact texture ;  as  in  the  Arum  triphyllum  or  Indian  Turnip  (Fig. 
144),  the  Colchicum,  the  Crocus  (Fig.  148),  the  Cyclamen,*  &c. 
It  may  be  compared  to  the  globular  stem  of  a  Melon-Cactus,  like 
which  it  has  no  power  of  elongation  ;  or  it  may  be  viewed  as  a 
tuber  or  rhizoma  reduced  to  the  greatest  simplicity,  developing  one 
or  more  buds  from  its  summit,  and  emitting  roots  from  its  base. 
Corms  are  often  termed  solid  hulbs;  and,  indeed,  they  are  only  a 


*  The  broad  and  flattened  corm  of  Cyclamen  arises  from  the  dilatation  of 
the  first  internode  of  the  stem,  that  which  preexists  in  the  embryo  below  the 
cotyledons  or  seed-leaves.  In  many  plants,  this  internode,  or  that  immedi- 
ately above  the  cotyledons,  enlarges  with  the  root.  This  occurs  in  the  Tur- 
nip, Radish,  Beet,  &c,;  where  the  root  thus  produced,  or  at  least  the  upper 
part  of  it,  presents  the  structure  of  the  stem. 

FIG.  139.  Base  of  the  stem  of  the  Jerusalem  Artichoke  (Helianthus  tuberosus),  showing  the 
nature  of  the  tubers. 

FIG.  140.  A  monstrous  branch  or  bud  of  the  Potato,  showing  a  transition  to  the  tuber; 
(From  the  Gardener's  Chronicle.) 

10 


no 


THE    STEM. 


kind  of  bulb  with  the  axis  more  enlarged,  and  the  investing  scales 
either  wholly  wanting,  as  in  the  Indian  Turnip  (Fig.  144),  or  very 
few,  forming  a  thin  coating,  as  in  the  Colchicum  and  Crocus. 

177.  A  Bulb  is  a  permanently  abbreviated  stem,  mostly  shorter 
than  broad,  and  clothed  with  scales,  which  are  imperfect  and  altered 
leaves,  or  the  thickened  and  persistent  bases  of  ordinary  leaves. 
Or,  in  other  words,  it  is  a  scaly  and  usually  subterranean  bud,  with 
thickened  scales,  and  a  depressed  axis  which  never  elongates.  Its 
centre  or  apex  developes  above  the  herbaceous  stalk,  foliage,  and 
flowers  of  the  season,  and  beneath  it  emits  roots.  In  the  bulb,  the 
thickening  by  the  deposition  of  nutritive  matter  stored  for  future 
use  takes  place  in  the  leaves  or  scales  it  bears,  instead  of  the  stem 
itself,  as  in  the  preceding  forms.  The  scales  are  sometimes  sepa- 
rate, thick,  and  in  several  distinct  rows,  as  in  the  scaly  bulb  of  the 
Lily  (Fig.  141);  sometimes  broad  and  encircling  each  other  in 
concentric  layers,  as  in  the  tunicated  bulb  of  the  Onion  (Fig.  145). 


178.  BulbletS  are  small  aerial  bulbs,  or  buds  with  fleshy  scales, 
which  arise  in  the  axils  of  the  leaves  of  several  plants,  such  as  the 
common  Lilium  bulbiferum  of  the  gardens  (Fig.  143),  and  at 
length  separate  spontaneously,  falling  to  the  ground,  where  they 
strike  root,  and  grow  as  independent  plants.  In  the  Onion,  and 
other  species  of  Allium,  many  of  the  flower-buds  frequently  change 
to  bulblets.     They  plainly  show  the  identity  of  bulbs  with  buds. 


FIG.  141.    The  scaly  bulb  of  a  Lily.     142.  A  vertical  section  of  the  same,  forming  the  an- 
nual stalk.    143.  Axillary  bulblets  of  Lilium  bulbiferum.    144.  Corm  of  Arum  triphyllum. 


ITS    SUBTERRANEAN    MODIFICATIONS. 


Ill 


no.  The  regular  plan  of  increase  and  ramification  already  de- 
scribed prevails  in  these  extraordinary,  no  less  than  in  the  ordi- 
nary, forms  of  the  stem.  They  grow  and  branch,  or  multiply,  by 
the  development  of  terminal  and  axillary  buds.  This  is  perfectly 
evident  in  the  rhizoma  and  tuber,  and  is  equally  the  case  in  the 
corm  and  bulb.  The  stem  of  the  bulb  is  usually  reduced  to  a  mere 
plateau  (Fig.  146,  a),  which  produces  roots  from  its  lower  surface, 
and  leaves  (the  exterior  of  which  are  reduced  to  scales)  from  the 
upper  surface.  Besides  the  terminal  bud  (c),  which  usually  forms 
the  flower-stem,  lateral  buds  (b)  may  be  produced  in  the  axils  of 
the  leaves  or  scales.  One  or  more  of  these  may  develope  as  flow- 
ering stems  the  next  season,  and  thus  the  same  bulb  survive  and 
blossom  from  year  to  year  (as  is  the  case  with  the  Tulip,  Hya- 
cinth, &c.) ;  or  these  axillary  buds  may  themselves  become  bulbs, 
feeding  on  the  parent  bulb,  which  in  this  way  is  often  consumed  by 
its  own  offspring,  as  in  the  Garlic  (Fig.  147)  ;  or,  finally  separat- 
ing from  the  living  parent,  just  as  the  bulblets  of  the  Tiger  Lily 
fall  from  the  stem,  they  may  form  so  many  independent  individ- 


uals.    So  the  old  corm  of  the  Crocus  (Fig.  148)  produces  one  or 
two  new  ones  (a)  near  the  apex,  and  gradually  dies  as  they  devel- 

FIG.  145.     Section  of  a  tunicated  bulb  of  the  Onion. 

FIG.  146.    Longitudinal  section  of  the  bulb  of  the  Tulip,  showing  its  stem  (a)  and  buds 
(6,  c). 

FIG.  147. 

FIG.  143. 


Bulb  of  the  Garlic,  with  a  crop  of  young  bulba. 
Vertical  section  of  tlie  corm  of  Crocus  :  a,  new  buds. 


FIG.  149.    Vertical  section  of  the  corm  of  Colchicum,  with  the  withered  corm  of  the  preced- 
ing (a),  and  the  forming  one  (c)  for  the  ensuing'year. 


112  THE    STEM. 

ope.  That  of  the  Colchicum  produces  a  new  bud  near  the  base  of 
the  old,  upon  which  it  feeds,  and  is  in  turn  destroyed  by  its  own 
progeny  the  next  year  ;  so  that  we  observe  (Fig.  149),  a,  the  shriv- 
elled corm  of  the  year  preceding ;  &,  that  of  the  present  season  (a 
vertical  section) ;  and  c,  the  nascent  bud  for  the  ensuing  season. 

180.  Many  of  the  forms  which  the  stem  assumes  when  above 
ground  differ  as  much  from  the  ordinary  appearance  as  do  any  of 
these  subterranean  kinds  ;  as,  for  example,  the  globular  Melon-Cac- 
tus, the  columnar  Cereus,  and  the  jointed  Opuntia  or  Prickly  Pear. 

Sect.  IV.     The  Internal  Structure  of  the  Stem  in  General. 

181.  Having  considered  the  various  external  forms  and  appear- 
ances which  the  stem  exhibits,  and  its  mode  of  increase  in  length, 
our  attention  may  now  be  directed  to  its  internal  structure,  and 
mode  of  increase  in  diameter. 

182.  The  stem  embraces  in  its  composition  the  various  forms  of 
elementary  tissue  that  have  already  been  described  (Chap.  I.,  Sect. 
II.,  III.) ;  namely,  ordinary  cells,  woody  fibre,  and  vessels.  At 
first,  indeed,  it  consists  entirely  of  parenchyma  (51),  which  pos- 
sesses much  less  strength  and  tenacity  than  woody  tissue,  and  is 
therefore  inadequate  to  the  purposes  for  which  the  stem,  in  all  the 
higher  plants,  is  destined.  The  stem  of  a  Moss  or  a  Liverwort  is, 
in  fact,  composed  of  ordinary  cellular  tissue  alone ;  and  is  there- 
fore weak  and  brittle,  well  enough  adapted  to  the-  humble  size  of 
that  tribe  of  plants,  but  incapable  of  attaining  any  considerable 
height.  Accordingly,  as  soon  as  the  stems  of  all  the  Phfenogamous 
plants  begin  to  grow,  and  in  proportion  as  the  leaves  are  developed, 
woody  mingled  with  vascular  tissue  is  introduced,  woven  into  the 
original  cellular  fabric,  to  afford  the  requisite  toughness  and 
strength,  and  to  facilitate  the  rise  of  the  ascending  sap.  If  it 
accumulates  only  to  moderate  extent  in  proportion  to  the  paren- 
chyma, the  stem  remains  herbaceous  (159) ;  if  it  predominates  and 
continues  to  accumulate  from  year  to  year,  the  proper  woody  trunk 
of  a  shrub  or  tree  is  formed.  That  the  woody  and  vascular  tissues 
arise  from  cells,  which  from  an  early  period  take  a  peculiar  devel- 
opment, has  already  been  shown  (52-61). 

183.  The  cellular  part  of  the  stem  grows  with  equal  readiness, 
in  whatever  direction  the  forces  of  vegetation  act.  It  grows  verti- 
cally, to  increase  the  stem  in  length,  and  horizontally,  to  increase 


ITS    INTERNAL    STRUCTURE.  113 

its  diameter.  Into  this  the  elongated  cells  that  form  the  woody 
tissue  and  ducts  are  introduced  vertically ;  they  run  lengthwise 
through  the  stem  and  branches.  Hence,  the  latter  has  been  called 
the  longitudinal^  vertical^  or  perpendicular  system  (56,  64) ;  and 
the  cellular  part,  the  horizontal  system  of  the  stem.  Or  the  stem 
may  be  compared  to  a  web  of  cloth  ;  the  cellular  system  forming 
the  woof^  and  the  woody,  the  warp.  It  will  be  seen  hereafter,  that 
this  illustration  not  inaptly  represents  the  real  structure  of  the  stem. 

184.  The  diversities  in  the  internal  structure  of  the  stem  are 
principally  owing  to  the  different  modes  in  which  the  woody  or 
vertical  system  is  imbedded  in  the  cellular.  These  diversities  are 
reducible  to  two  general  plans ;  upon  one  or  the  other  of  which 
the  stems  of  all  Flowering  Plants  are  constructed.  Not  only  is  the 
difference  in  structure  quite  striking,  especially  in  all  stems  more 
than  a  year  old,  but  it  is  manifested  in  the  whole  vegetation  of  the 
two  kinds  of  plants,  and  indicates  the  division  of  Phsenogamous 
plants  into  two  great  classes,  recognizable  by  every  eye  ;  which,  in 
their  fully  developed  forms,  may  be  represented,  one  by  the  Oak 
and  the  other  trees  of  our  climate,  the  other  by  the  Palm  (Fig.  166). 

185.  The  difference  between  the  two,  as  to  the  structure  of  their 
stems,  is  briefly  and  simply  this.  In  the  first,  the  woody  system  is 
deposited  in  annual  concentric  layers  between  a  central  pith  and 
an  exterior  hark ;  so  that  a  cross-section  presents  a  series  of  rings 
or  circles  of  wood,  surrounding  each  other 
and  a  distinct  pith,  and  all  surrounded  by 
a  separable  bark.  This  is  the  plan  not 
only  of  the  Oak,  but  of  all  the  trees  and 
shrubs  of  the  colder  climates.  In  the 
second,  the  woody  system  is  not  disposed 
in  layers,  but  consists  of  separate  bundles 
or  threads  of  woody  fibre,  &c.,  running  through  the  cellular 
system  without  apparent  order ;  and  presenting  on  the  cross-sec- 
tion a  view  of  the  divided  ends  of  these  threads  in  the  form  of  dots, 
diffused  through  the  whole ;  but  with  no  distinct  pith,  and  no  bark 
which  is  at  any. time  readily  separable  from  the  wood.  The  ap- 
pearance of  such  a  stem,  both  on  the  longitudinal  and  the  cross- 
section,  is  shown  in  Fig.  150  ;  it  may  also  be  examined  in  the  Cane 
or  Rattan,  the  Bamboo,  and  in  the  ai;>nual  stalk  of  Indian  Corn  or 

FIG.  150.    Section  of  a  Palm-stem. 

10* 


114  THE    STEM. 

of  Asparagus.     That  of  ordinary  wood  of  the  first  sort  is  too  famil- 
iar to  need  a  pictorial  illustration. 

186.  Exogenous  Structure.  The  stem,  in  the  first  case,  increases 
in  diameter  by  the  annual  formation  of  a  new  layer  of  wood,  which 
is  deposited  between  the  preceding  layer  and  the  bark ;  in  other 
words,  the  wood  increases  by  annual  additions  to  its  outside. 
Hence,  such  stems  are  said  to  have  the  Exogenous  structure  ;  and 
the  plants  whose  stems  grow  in  this  way  are  called  Exogenous 
Plants,  or  briefly  Exogens  ;  that  is,  as  the  term  literally  signi- 
fies, outside- growers. 

187.  Endogenous  Structure.  In  the  second  case,  the  new  woody 
matter  is  intermingled  with  the  old,  or  deposited  towards  the  cen- 
tre, which  becomes  more  and  more  occupied  with  the  woody 
threads  as  the  stem  grows  older ;  and  increase  in  diameter,  so  far 
as  it  depends  on  the  formation  of  new  wood,  generally  takes  place 
by  the  gradual  distention  of  the  whole,  the  new  wood  pushing  the 
old  outwards.  Accordingly,  these  stems  are  said  to  exhibit  the 
Endogenous  structure  or  growth  ;  and  such  plants  are  called  En- 
dogenous Plants,  or  Endogens  ;  literally,  inside-growers. 

188.  The  two  great  classes  of  Pha3nogamous  plants,  indicated 
by  this  difference  in  the  stem,  are  distinguishable  even  in  the  em- 
bryo state,  by  differences  quite  as  marked  as  those  which  prevail 
in  their  whole  port  and  aspect.  The  embryo  of  all  plants  that 
have  endogenous  stems  bears  only  a  single  cotyledon,  and  there- 
fore sends  up  but  one  seed-leaf  in  germination ;  hence,  Endogens 
are  also  called  Monocotyledonous  Plants.  The  embryo  of 
plants  with  exogenous  stems  bears  a  pair  of  cotyledons  and  un- 
folds a  pair  of  seed-leaves  in  germination  (Fig.  105-  107)  :  hence 
Exogens  are  likewise  called  Dicotyledonous  Plants. 

Sect.  V.     The  Exogenous  or  Dicotyledonous  Stem. 

189.  Since  the  Exogenous  class  is  by  far  the  largest  in  every 
part  of  the  world,  and  embraces  all  the  trees  and  shrubs  with 
which  we  are  familiar  in  the  cooler  climates,  the  structure  of 
this  kind  of  stem  demands  the  earlier  and  more  detailed  notice. 
To  obtain  a  true  and  clear  idea  of  its  internal  structure,  we  should 
commence  at  its  origin  and  follow  the  course  of  development. 

190.  In  the  embryo  state,  or  at  least  at  some  period  antecedent 
to  germination,  the  rudimentary  stem  is  entirely  composed  of  pa- 


EXOGENOUS    STRUCTURE.  115 

renchyma.  But  as  soon  as  it  begins  to  grow,  while  the  cotyledons 
only  are  developing  (as  in  Fig.  106, 107),  some  of  the  cells  begin  to 
lengthen  into  tubes,  to  be  marked  with  transverse  bars  or  spiral 
lines,  and  thus  give  rise  to  ducts  or  vessels  (57-60);  these  are 
grouped  as  they  form  into  a  small  and  definite  number  of  bundles 
or  threads,  say  four  equidistant  ones  in  the  first  instance,  as  in  the 
Sugar  Maple  :  other  slender  cells  of  smaller  calibre,  and  destitute 
of  markings,  soon  appear  surrounding  the  threads  of  vessels,  and 
forming  the  earliest  woody  tissue.  As  the  rudiments  of  the  next 
internode  and  its  leaves  appear,  two  or  four  additional  threads  of 
vascular  tissue  appear  in  the  stem  below,  in  the  parenchyma  be- 
tween the  earliest  ones,  and  equally  surrounded  with  forming 
woody  tissue.  At  an  early  stage,  therefore,  the  developing  stem 
is  seen  to  be  traversed  by  several  bundles  of  woody  tissue  with 
some  vessels  imbedded ;  and  these,  as  they  increase  and  enlarge, 
run  together  so  as  to  make  up  a  woody  sheath,  or,  as  seen  in  the 
cross-section,  a  ring,  inclosing  the  central  part  of  the  parenchyma 
within  it,  and  itself  inclosed  by  the  external  parenchyma.  Thus 
a  circle  or  layer  of  wood  is  formed,  which  is  in  such  a  way  im- 
bedded in  the  original  homogeneous  cellular  system  as  to  divide  it 
into  two  parts ;  namely,  a  central  portion,  which  forms  the  pith, 
and  an  exterior  zone,  which  belongs  to  the  bark.  The  whole  is  of 
course  invested  by  the  skin  or  epidermis,  which  covers  the  entire 
surface  of  the  plant.  The  way  in  which  the  layer  of  wood  thus 
originates  is  somewhat  rudely  illustrated  by  the  annexed  diagrams 
(Fig.  151  -  153).  The  several  woody  masses,  especially  in  trees 
and  shrubs,  are  separated  from  each  other  by  lines  or  bands  of  the 
original  cellular  tissue  which  pass  from  the  pith  to  the  bark,  and 
which  necessarily  become  narrower  and  more  numerous  as  the 
woody  bundles  or  wedges  increase  in  size  and  number.  These 
are  the 

191.  Medullary  Rays,  which  form  the  radiating  lines  that  the 
cross-section  of  most  exogenous  wood  so  plainly  exhibits,  espe- 
cially that  of  the  Oak,  Plane,  &c.  They  are  the  remains  or  the 
cellular  system  of  that  part  of  the  stem,  condensed  by  the  pressure 
of  the  woody  wedges,  or  plates,  and  which  serve  to  keep  up  the 
communication  between  the  pith  and  the  bark. 

192.  The  First  Year's  Growth  of  an  exogenous  stem  accordingly 
consists  of  three  principal  parts ;  namely,  1st,  a  central  cellular 
portion,  or  Pith ;  2d,  a  zone  of  Wood  ;  and  3d,  an  exterior  cellular 


116 


THE    STEM. 


portion,  or  Bork.  Fig.  154  represents  a  section  of  a  woody  exoge- 
nous stem,  a  year  old,  of  the  natural  size.  Fig.  155  shows  a  por- 
tion of  the  same,  magnified,  so  that  the  different  parts  may  be  dis- 
tinguished, both  on  the  longitudinal  and  transverse  section :  and 
Fig.  156  is  a  much  more  magnified  view  of  a  slice  of  the  same, 
reaching  from  the  bark  to  the  pith. 


193.  The  Pilh  (Fig.  155,  156,  a)  consists  entirely  of  soft  cellu- 
lar tissue,  or  parenchyma  (51),  which  is  at  first  gorged  with  the 
nourishing  juices  of  the  plant.  These  are  in  time  exhausted,  leav- 
ing the  older  pith  dry  and  light,  or  mere  empty  cells,  which  are  of 
no  further  use  to  the  plant.  Many  stems  expand  so  rapidly  in  di- 
ameter during  their  early  growth,  that  they  become  hollow,  the  pith 
being  torn  away  by  the  distention,  its  remains  forming  a  mere  lining 
to  the  cavity,  as  in  Grasses  and  other  herbs  ;  or  else  it  is  separated 
into  horizontal  plates,  as  in  the  Poke  (Phytolacca)  and  the  Wal- 
nut. Immediately  surrounding  the  pith,  and  the  very  earliest  part 
of  the  longitudinal  system  to  appear,  is  what  is  called  by  the  su- 
perfluous name  of 

194.  The  Medullary  Sheath,  This  consists  merely  of  the  earliest 
formed  vessels,  already  spoken  of  (190),  and  which  of  course  stand 
in  a  circle  immediately  surrounding  the  pith;  but  they  are  seldom 
if  ever  so  numerous  as  to  form  a  closed  layer,  or  sheath  for  the  pith. 
More  commonly  they  appear  as  a  few  bundles,  one  at  the  inner 
border  of  each  of  the  larger  and  earlier  woody  wedges.  They 
are  mostly  of  the  kind  named  spiral  vessels  (60),  and  it  is  remark- 

FIG.  151.  Plan  of  a  cross-section  of  a  young  seedling  stem,  showing  the  manner  in  which 
the  young  wood  ia  imbedded  in  the  cellular  system. 

FIG.  152,  The  same  at  a  later  period,  the  woody  bundles  increased  so  as  nearly  to  fill  the 
circle. 

FIG.  153.  The  same  at  the  close  of  the  season,  where  the  wood  has  formed  a  complete  cir- 
cle, separating  the  pith  from  the  bark,  except  that  they  are  still  connected  by  narrow  portions 
of  the  cellular  system  (the  medullary  rays)  which  radiate  from  the  pith  to  the  bark. 


EXOGENOUS    STRUCTURE. 


117 


MM 


able  that  this  is  the  only  part  of  an  exogenous  stem  in  which  spiral 
vessels     ordinari-  ^^ 

]y  occur.  They 
may  be  detected 
by  breaking  a 
woody  twig  in 
two,  after  dividing 
the  bark  and  most 
of  the  wood  by  a 
circular  incision, 
and  then  pulling 
the  ends  gently 
asunder,  when 
their  spirally  coil- 
ed fibres  are  read- 
ily drawn  out  as 
gossamer  threads. 
They  are  shown 
in  place  in  the 
vertical  section, 
Fig.  156,  h. 

195.  The  Wood 
(Fig.  156,  c)  con- 
sists    of     proper 

woody  tissue,  among  which  the  vascular  is  more  or  less  copiously 
mingled,  principally  in  the  form  of  dotted  ducts  (d)^  or  occasion- 
ally some  spiral  or  annular  ducts  (e),  &c.  The  dotted  ducts  are  of 
so  considerable  calibre,  that  they  are  conspicuous  to  the  naked  eye 
in  many  ordinary  kinds  of  wood,  especially  where  they  are  accu- 
mulated in  the  inner  portion  of  each  layer,  as  in  the  Chestnut  and 
Oak.  In  the  Maple,  Plane,  &c.,  they  are  nearly  equably  scattered 
through  the  annual  layer,  and  are  of  a  size  so  small  that  they  are 
not  distinguishable  to  the  naked  eye. 


FIG.  154.  Longitudinal  and  transverse  section  of  a  stem  of  the  Soft  Maple  (Acer  dasycar- 
pum)  at  the  close  of  the  first  year's  growth  ;  of  the  natural  size. 

FIG.  155.  Portion  of  the  same,  magnified,  showing  the  cellular  pith,  surrounded  by  the 
wood,  and  that  inclosed  by  the  bark. 

FIG.  156.  More  magnified  slice  of  the  same,  reaching  from  the  bark  to  the  pith:  a,  part  of 
the  pith;  6,  vessels  of  the  medullary  sheath;  c,  the  wood;  dd,  dotted  ducts  in  the  wood;  ee, 
annular  ducts;  /,  the  liber,  or  inner,  fibrous  bark;  g,  the  cellular  envelope,  or  green  bark;  h, 
the  corky  envelope  ;  i,  the  skin  or  epidermis;  j,  one  of  the  medullary  rays,  seen  on  the  trans- 
verse section. 


118 


THE    STEM. 


196.  The  vertical  section  in  Fig.  156  passes  directly  through 
the  middle  of  one  of  the  woody  plates  that  collectively  compose 
the  layer ;  and  therefore  the  medullary  rays  do  not  appear.  But 
in  the  much  more  magnified  Fig.  157,  the  section  is  made  so  as  to 
show  the  surface  of  one  of  these  plates,  and  one  of  the  Medullary 
Rays  passing  horizontally  across  it,  connecting  the  pith  (;;)  with 
the  bark  (b).  These  medullary  rays  form  the  silver-grain,  (as  it 
is  termed,)  which  is  so  conspicuous  in  the  Maple,  White  Oak,  Red 
Oak,  &c.,  and  which  gives  the  glimmering  lustre  to  many  kinds 
of  wood  when  cut  in  this  particular  direction.  But  a  section  made 
as  a  tangent  to  the  circumference,  and  therefore  perpendicular  to 
the  medullary  rays,  brings  their  ends  to  view,  as  in  Fig.   158; 


fconnnc^ar 


^ocDcSl 


jaaefrp-^— ^-^-^^-^-•^^^' 


laOCar 


much  as  they  appear  when  seen  on  the  surface  of  a  piece  of  wood 
from  which  the  bark. is  stripped.  They  are  evidently  composed  of 
condensed  parenchyma  merely,  and  their  origin  has  already 
been  explained  (191).  They  represent  the  horizontal  system  of 
the  wood,  or  the  woof,  into  which  the  vertical  woody  fibre,  &c.,  or 
warp,  is  interwoven.  .  The  inspection  of  a  piece  of  oak  or  maple 
wood  at  once  shows  the  pertinency  of  this  illustration. 

197.  The  Bark,  in  a  stem  of  a  year  old,  must  next  be  more  atten- 
tively considered.  At  first  it  consisted  of  simple  cellular  tissue,  or 
parenchyma,  undistinguishable  from  that  of  the  pith,  except  that 
it  assumed  a  green  color  when  exposed  to  the  light,  from  the  pro- 
duction of  chlorophyll  (87)  in  its  superficial  cells.  But  during  the 
formation  of  the  proper  wood,  an  analogous  formation  occurs  in 


FIG.  157.  Vertical  sectioa  through  the  wood  of  a  branch  of  the  Maple,  a  year  old;  so  as  to 
show  one  of  the  medullary  rays,  passing  transversely  from  the  pith  (p)  to  the  bark  (h) :  magni- 
fied. But  a  section  can  seldom  be  made  so  as  to  show  one  unbroken  plate  stretching  across  the 
wood,  as  in  this  instance. 

FIG.  158.    A  vertical  section  across  the  ends  of  the  medullary  rays;  magnified. 


EXOGENOUS  STRUCTURE.  119 

llie  bark.  The  inner  portion,  next  the  wood,  has  woocly  tissue 
formed  in  it,  and  becomes 

198.  The  Liber,  or  Fibrous  Inner  Bark  (Fig.  156,/).  These 
fibre-like  cells,  which  give  to  the  inner  bark  of  those  plants  that 
largely  contain  them  its  principal  strength  and  toughness,  are  of 
the  kind  already  described  under  the  name  of  hast-ceUs  or  iast- 
tissue  (55).  They  are  remarkable  for  their  length,  flexibility,  and 
the  great  thickness  of  their  walls.  They  are  deposited  as  detach- 
ed bundles,  or  in  bands  separated  by  extensions  of  the  medullary 
rays,  one  accordingly  corresponding  to  each  of  the  woody  plates 
or  wedges,  or  sometimes  (as  in  Negundo,  Fig.  159,  160)  they  are 
confluent  into  an  unbroken  circle  round  the  whole  circumference. 
The  liber  has  received  the  technical  name  of  Endophl^um  (liter- 
ally inner  hark).  The  exterior  part  of  the  bark,  in  which  no 
woody  tissue  occurs,  is  early  distinguishable,  in  most  stems,  into 
two  parts,  an  inner  and  an  outer.     The  former  is 

199.  The  Cellular  Envelope,  or  Green  Layer  (Fig.  156,  g),  also 
called,  from  its  intermediate  position,  the  Mesophl-Eum.  This  is 
composed  of  loose  parenchyma,  with  thin  walls,  much  like  the 
green  pulp  of  leaves  (which  last  is,  indeed,  an  outlying  part  of  the 
same  system),  and  containing  an  equal  abundance  of  chlorophyll. 
It  is  the  only  part  of  the  bark  that  retains  a  green  color.  In 
woody  stems  this  is  covered  with 

200.  The  Corky  Envelope,  or  Epiphljeum  (Fig.  156,  b),  which 

gives  to  the  twigs  of  trees  and  shrubs  the  hue  peculiar  to  each  spe- 
cies, generally  some  shade  of  ash-color  or  brown,  or  occasionally 
of  much  more  vivid  tints.  It  is  rarely  colored  green,  as  in  Ne- 
gundo, where  the  inner  cells  contain  chlorophyll.  It  is  this  tissue, 
which,  taking  an  unusual  development,  forms  the  cork  of  the  Cork- 
Oak,  and  those  corky  expansions  of  the  bark  which  are  so  con- 
spicuous on  the  branches  of  the  Sweet  Gum  (Liquidambar),  of 
some  of  our  Elms  (Ulmus  alata  and  racemosa),  &c.  It  also  forms 
the  paper-like  exfoliating  layers  of  Birch-bark.  It  is  composed  of 
laterally  flattened  parenchymatous  cells,  much  like  those  of  the 
Epidermis  (Fig.  156,  i),  which  directly  overlies  it,  and  forms  the 
skin  or  external  surface  of  the  stem. 

201.  To  recapitulate  the  elements  which  compose  the  fabric  of 
an  exogenous  stem  of  a  year  old,  especially  in  a  woody  plant,  and 
at  the  same  time  to  exhibit  them  in  an  accurately  drawn,  more 
magnified  view,  we  have,  proceeding  from  the  centre  towards  the 
circumference, — 


120 


THE    STEM. 


I.  In  the  Wood  : 

1.  The  Pith,  belonging  to  the  cellular  system  (Fig.  159, 160,;?). 

2.  The  Medullary  Sheath,  ms,  ')  which  belong  to  the  woody  or 

3.  The  Layer  of  Wood,  TF,  w,  \      longitudinal  system. 

4.  The  Medullary  Rays,  mr,  a  part  of  the  cellular  system. 

11.  In  the  Bark  : 

5.  The  Liher,  I ;  its  bast  tissue,  b,  belongs  to  the  woody  system. 

6.  Tlie  Outer  Bark,  belonging  wholly  to  the  cellular  system, 

and  composed  of  two  parts ;  namely,  1st,  the  Green  or  Cel- 
lular Envelope,  ge,  and  2d,  the  Corky  Envelope,  ce. 

7.  The  Epidermis,  e,  or  skin,  which  invests  the  whole. 


\/ 


-\r 


FIG.  159.  Portion  of  a  transverse  section,  and  160,  a  corresponding  vertical  section,  magni- 
fied, reaching  from  the  pith,  p,  to  the  epidermis,  e,  of  a  stem  of  Negundo,  a  year  old:  B,  the 
bark ;  W,  the  wood ;  and  C,  the  cambium-layer,  as  found  in  February.  The  references  are  in 
the  text  above;  except  mr,  portion  of  a  medullary  ray,  seen  on  the  vertical  section,  where  it 
runs  into  the  pith :  dd,  dotted  ducts :  cl,  the  inner  part  of  the  cambium-layer,  which  begins 
the  new  layer  of  wood  In  this  tree,  we  find  a  Ihicic  layer  of  parenchyma  (/)  inside  of  the  bast 
tissue,  and  therefore  belonging  to  the  liber.    No  bast  tissue  is  formed  in  it  the  second  year. 


EXOGENOUS  STRUCTURE.  121 

202.  An  herbaceous  stem  does  not  essentially  differ  from  a 
woody  one  of  this  age,  except  that  the  wood  forms  a  less  dense  and 
thinner  zone  ;  and  the  whole  perishes,  at  least  down  to  the  ground^ 
at  the  close  of  the  season.  But  a  shrubby  or  arborescent  stem 
makes  provision  for  an  addition  to  its  fabric  the  second  year,  — 
which  may  now  be  considered. 

203.  Cambium-layer.  The  wedges  which  constitute  the  woody 
layer  usually  increase  in  thickness  throughout  the  season,  by  the 
continued  development  of  prosenchymatous  cells  on  their  outer 
face,  and  the  medullary  rays  extend  equally  by  the  multiplication 
of  parenchymatous  cells  :  so  that  there  is  always  a  thin  stratum  of 
delicate  forming  and  growing  cells  interposed  between  the  wood 
and  the  bark.  This  is  called  the  Cambium-layer  (Fig.  159, 
160,  C).  It  survives  the  winter  in  all  exogenous  stems  capable  of 
more  than  one  year's  growth,  remaining  latent  during  the  suspen- 
sion of  vegetation,  and  resuming  its  activity  in  the  spring,  to  give 
rise  to 

204.  The  Second  Year's  Growth  in  Diameter.  In  spring,  when  vege- 
tation vigorously  recommences,  and  the  buds  are  developing  the 
onward  growth  of  the  season,  a  portion  of  the  sap,  charged  with 
mucilage  (dextrine,  protoplasm,  &c.),  is  at  the  same  time  attracted 
into  the  cambium-layer,  as  into  every  part  where  growth  is  going 
on ;  and  the  bark,  before  adherent,  is  now  readily  separable  from 
the  wood.  To  this  mucilaginous  organizable  matter  the  name  of 
Cambium  was  long  ago  applied,  and  hence  the  forming  stratum  is 
termed  the  cambium-layer ;  but  the  latter  is  only  an  incipient  new 
woody  layer ;  and  the  cambium  is  nothing  more  than  ordinary 
sap,  well  charged  with  dissolved  assimilated  matters,  accumulated 
at  the  part  of  the  woody  stem  where  further  growth  alone  takes 
place,  and  serving  as  the  materials  for  such  growth.  It  is  quite 
wrong  to  suppose  that  there  is  a  real  interruption'  between  the 
wood  and  the  bark  at  this,  or  any  other  period,  leaving  a  space 
filled  with  extravasated  sap.  A  series  of  delicate  slices  will  at  any 
time  show  that  the  bark  and  the  wood  are  always  organically  con- 
nected, by  a  very  delicate  tissue  of  vitally  active,  partly  grown 
cells,  just  in  the  state  in  which  they  multiply  by  division  (26,  32). 
It  is  when  this  process  of  growth  is  most  rapidly  going  on,  in 
spring  or  early  summer,  and  the  whole  cambium-layer  is  gorged 
by  the  flow  of  sap,  that  the  bark  is  so  easily  separable ;  but  the 
separation  is  effected  by  the  rending  of  a  delicate  new  tissue.    The 

11 


KS  THE    STEM. 

inner  portion  of  this  cambium-layer  is  forming  wood  ;  the  outer  is 
forming  bark.  The  cells  of  the  first  multiply  vertically  by  divis- 
ion, and  then  elongate  into  prosenchyma  or  woody  tissue,  a  part 
of  them  being  at  the  same  time  commonly  transformed  into  ducts ; 
thus  producing  a  second  layer  of  wood  on  the  surface  of  the 
first,  and  continuous  with  the  primary  layer  in  the  prolongation  of 
the  stem  and  in  the  branches  made  the  same  season.  The  exte- 
rior part  of  the  cambium-layer  contributes  in  much  the  same  way 
to  the  thickness  of  the  liber,  which  therefore  grows  inversely,  or 
by  accessions  to  its  inner  face.  But  the  bark  exhibits  such  great 
diversities  in  growth  and  structure,  that  it  cannot  well  be  farther 
considered  along  with  the  wood. 

205.  Annual  Increase  of  the  Wood.  Each  successive  year  a  new 
layer  is  added  to  the  wood  in  the  same  manner ;  each  layer  being, 
like  the  first,  intersected  by  the  extended  medullary  rays.  A 
cross-section  of  such  a  stem,  therefore,  exhibits  the  wood  disposed 
in  concentric  rings  between  the  bark  and  the  pith  ;  the  oldest  lying 
next  the  latter,  or  in  the  centre,  and  the  youngest  occupying  the 
circumference.  Each  layer  being  the  product  of  a  single  year's 
growth,  the  age  of  an  exogenous  tree  may,  in  general,  be  correctly 
ascertained  by  counting  the  rings  in  a  cross-section  of  the  trunk. 
It  is  obvious,  moreover,  that  the  growing  parts  of  an  exogenous 
tree  or  shrub  (and  the  same  applies  to  the  herb)  are,  —  1.  The  apex 
of  the  stem  and  branches,  by  buds,  which  continue  the  plant  up- 
wards and  develope  the  foliage.  2.  The  lower  extremity  of  the 
roots,  by  which  these  are  advanced  from  year  to  year.  3.  The 
cambium-layer,  which  annually  produces  a  stratum  of  fresh  tissue 
under  the  bark,  between  the  buds  and  the  rootlets,  over  the  whole 
extent  of  the  plant ;  its  ordinary  growth  giving  rise  to  new  annual 
layers  of  wood  and  inner  bark ;  while  certain  cells,  taking  a  spe- 
cial development,  form  buds  and  consequently  branches  in  the  axils 
of  the  leaves,  or,  adventitiously  (152),  from  other  places,  or  else, 
under  favoring  circumstances,  secondary  or  adventitious  roots 
(130).  Lateral  buds  and  roots,  although  they  originate  in  the 
cambium-layer,  have  to  grow  and  break  through  the  bark  before 
they  appear  externally.* 


*  That  peculiar  state  of  the  wood  of  the  Sugar  Maple,  called  Bird's-eye 
Maple,  is  apparently  caused  by  numberless  rudimentary  adventitious  buds, 
which,  failing,  to  grow,  have  become  involved  in  the  woody  layers. 


EXOGENOUS  STRUCTURE.  123 

206.  The  limits  of  each  year's  growth  in  diameter  in  exogenous 
wood  are  apparent  in  the  cross-section  in  the  form  of  concentric  lay- 
ers, from  two  causes,  either  separate  or  combined  ;  viz.,  the  greater 
abundance  of  ducts  in  the  earlier  part  of  each  annual  increment, 
and  the  smaller  size  of  the  woody  fibres  in  the  latest  growth  of  the 
season,  which  is  destitute  of  ducts,  and  forms  a  finer-grained  bor- 
der to  the  ring.  This  is  well  shown  in  the  cross-section  of  bass- 
wood,  where  the  ducts  compose  the  greater  part  of  the  wood  at  the 
inner  edge  of  each  layer,  and  very  gradually  diminish  in  number 
towards  the  outer  edge,  which  is  marked  by  a  thin  stratum  of  mi- 
nute, laterally  flattened  wood-cells ;  —  probably  a  portion  of  the 
cambium-layer  that  took  no  further  growth.  This  fine  exterior 
border  alone  marks  the  layers  in  white-pine  wood,  where  there 
are  no  ducts  or  other  vessels  interspersed,  and  in  such  wood  as 
that  of  the  Sugar  Maple,  where  the  ducts  are  somewhat  equably 
distributed  through  the  whole  breadth  of  the  layer.  In  oak  and 
chestnut  wood,  the  layers  are  most  strikingly  marked,  by  the  ac- 
cumulation of  all  the  large  dotted  ducts,  here  of  extremely  great 
size  and  abundance,  in  the  inner  portion  of  each  layer,  where 
their  open  mouths  on  the  cross-section  are  conspicuous  to  the 
naked  eye,  making  a  strong  contrast  between  the  inner  porous, 
and  exterior  solid  part  of  the  successive  layers. 

207.  The  annual  layers  are  most  distinct  in  trees  of  temperate 
climates  like  ours,  where  there  is  a  prolonged  period  of  total  re- 
pose, from  the  winter's  cold,  followed  by  a  vigorous  resumption  of 
vegetation  in  spring.  In  tropical  trees  they  are  rarely  so  well  de- 
fined ;  but  even  in  these  climes  there  is  generally  a  more  or  less 
marked  annual  suspension  of  vegetation,  occurring,  however,  in 
the  dry  and  hotter,  rather  than  in  the  cooler  season.  There  are 
numerous  cases,  moreover,  in  which  the  wood  forms  a  uniform 
stratum,  whatever  be  the  age  of  the  trunk,  as  in  the  arborescent 
species  of  Cactus ;  or  where  the  layers  are  few  and  by  no  means 
corresponding  with  the  age  of  the  trunk,  as  in  the  Cycas. 

208.  In  many  woody  climbing  or  twining  stems,  such  as  those 
of  Clematis,  Aristolochia  Sipho,  and  Menispermum  Canadense,  the 
annual  layers  are  obscurely,  if  at  all,  marked,  while  the  medullary 
rays  are  unusually  broad,  and  the  wood  therefore  forms  a  series  of 
separable  wedges  disposed  in  a  circle  around  the  pith.  In  the 
stem  of  one  of  our  Trumpet-creepers  (the  Bignonia  capreolata) 
the  annual  rings,  after  the  first  four  or  five,  are  interrupted  in  four 


124  THE    STEM. 

places,  and  here  as  many  broad  plates  of  cellular  tissue,  belonging 
properly  to  the  bark,  are  interposed,  passing  at  right  angles  to 
each  other  from  the  circumference  towards  the  centre,  so  that  the 
transverse  section  of  the  wood  nearly  resembles  a  Maltese  cross. 
But  these  are  all  exceptional  cases,  which  scarcely  require  notice 
in  a  general  view. 

209.  The  wood  of  the  Pine,  Yew,  Cypress,  and  the  whole  tribe 
of  what  are  called  Coniferce,  or  cone-bearing  trees,  is  character- 
ized by  its  uniformity  of  structure,  being  formed  of  a  peculiar 
woody  tissue  with  little  or  no  intermixture  of  true  ducts,  and  by 
having  the  walls  of  these  woody  tubes  marked  with  large  circular 
discs,  as  in  Fig.  23  (45,  54). 

210.  Sap-wood  and  Heart-wood.  In  the  germinating  plantlet  and 
in  the  developing  bud,  the  sap  ascends  through  the  whole  tissue  of 
whatever  sort ;  at  first  through  the  parenchyma,  for  there  is  then 
no  other  tissue  ;  and  the  transmission  is  continued  through  it,  espe- 
cially through  its  central  portion,  or  the  pith,  in  the  growing  apex 
of  the  stem  throughout.  But  in  the  older  parts  below,  the  pith  is 
soon  drained  of  sap  by  the  demand  above,  and  becomes  filled  with 
air  in  its  place  :  thenceforth  it  bears  no  part  in  the  plant's  nourish- 
ment. As  soon  as  wood -cells  and  ducts  are  formed,  they  take  an 
active  part  in  the  conveyance  of  sap  ;  for  which  their  tubular  and 
capillary  character  is  especially  adapted.  But  the  ducts  in  older 
parts,  except  when  gorged  with  sap,  contain  air  E^lone  ;  and  the 
sap  now  continues  to  rise  only  or  chiefly  through  the  stem,  year 
after  year,  to  the  places  where  growth  is  going  on,  through  the 
proper  woody  tissue  of  the  wood.  In  this  transmission,  the  new 
and  fresh  tissues  are  the  most  active.  The  walls  of  the  cells  that 
compose  them  soon  begin  to  thicken  by  internal  deposition  and  by 
incrustation  with  mineral  matters  introduced  with  the  sap  (39,  40, 
53) ;  and  by  the  formation  of  new  annual  layers  outside  of  them, 
their  predecessors  are  each  year  removed  a  step  farther  from  the 
region  of  growth ;  or  rather  the  growing  stratum,  which  connects 
the  fresh  rootlets,  that  imbibe,  with  the  foliage,  that  elaborates,  the 
sap,  is  each  year  removed  farther  from  them.  The  latter,  there- 
fore, after  a  few  years,  cease  to  convey  sap,  as  they  have  long 
before  ceased  to  take  part  in  any  vital  operations.  This  older, 
more  solidified,  and  harder  wood,  which  occupies  the  centre  of  the 
trunk  and  is  the  part  principally  valuable  for  timber,  &c.,  is  called 
Heart-wood,  or  Duramen  :    while  the  newer  layers  of  softer, 


EXOGENOUS    STRUCTURE. 


125 


more  open  and  bibulous  wood,  wbich  is  apt  to  be  surcharged  with 
sap,  receive  the  name  of  Sap-wood,  or  Alburnum.  The  latter 
name  was  given  by  the  earlier  physiologists  in  allusion  to  its  white 
or  pale  color.  In  all  trees  which  have  the  distinction  between 
the  sap-wood  and  heart-wood  well  marked,  the  latter  acquires  a 
deeper  color,  and  that  peculiar  to  the  species,  such  as  the  dark 
brown  of  the  Black  Walnut,  the  blacker  color  of  the  Ebony,  the 
purplish-red  of  Red  Cedar,  and  the  bright  yellow  of  the  Barberry. 
These  colors  are  owing  to  special  vegetable  products  mixed  with 
the  incrusting  matters  ;  but  sometimes  the  hue  appears  to  be  rather 


an  alteration  of  the  lignine  with  age.     In  the  Red  Cedar,  the  deep 
color  belongs  chiefly  to  the  medullary  rays.     To  show  that  the 


FIG.  161,  Magnified  cross-section  of  a  portion  of  woody  tissue  of  White  Oak,  a  year  old. 
162.  A  longitudinal  as  well  as  cross  section  of  the  same,  a  little  higher  magnified,  a,  a,  Por- 
tions of  one  of  the  smaller  medullary  rays. 

FIG.  163.    Magnified  cross-section  of  woody  tissue  from  the  same  stem,  taken  from  a  layer 
of  heart-wood,  24  years  old :  h,  ducts  :  a,  portion  of  one  of  the  minuter  medullary  rays,     164. 
Combined  cross  and  longitudinal  section  of  the  same :  a,  tissue  of  a  medullary  ray, 
11* 


126  THE    STEM. 

older  wood-cells  are  more  solidified  than  the  new,  the  annexed 
figures  are  given  from  corresponding  parts  of  the  same  trunk  of 
White  Oak;  Fig.  161,  162,  from  sap-wood  a  year  old;  Fig.  163, 
164,  from  a  layer  of  heart-wood  twenty-four  years  old.  The  walls 
in  both  are  greatly  thickened  with  lignine ;  but  in  the  latter  the 
calibre  of  a  large  part  of  the  cells  is  almost  obliterated.  In  many 
of  the  softer  woods,  there  is  little  solidification  in  this  way,  and 
scarcely  any  change  in  color  of  the  heart-wood,  except  from 
incipient  decay,  as  in  the  White  Pine,  Poplar,  Tulip-tree,  &c. 

211.  Each  layer  of  wood,  once  formed,  remains  unaltered  in 
dimensions  and  position,  and  unchangeable  except  from  internal 
deposition  and  from  decay.  The  heart- wood  is  no  longer  in  any 
sense  a  living  part  of  the  tree ;  it  may  perish,  as  it  frequently 
does,  without  affecting  the  life  of  the  tree. 

212.  The  Bark  is  much  more  various  in  structure  and  growth 
than  the  wood  :  it  is  also  subject  to  grave  alterations  with  advan- 
cing age,  on  account  of  its  external  position,  to  distention  from  the 
constantly  increasing  diameter  of  the  stem  within,  and  to  abrasion 
and  decay  from  the  influence  of  the  elements  without.  It  is  never 
entire,  therefore,  on  the  trunks  of  large  trees ;  but  the  dead  exte- 
rior parts,  no  longer  distending  with  the  enlarging  wood,  are  grad- 
ually fissured  and  torn,  and  crack  off  in  layers,  or  fall  away  by 
slow  decay.  So  that  the  bark  of  old  trunks  bears  but  a  small 
proportion  in  thickness  to  the  wood,  even  when  it  makes  an  equal 
annual  growth. 

213.  The  three  constituent  strata  (197-200),  for  the  most  part 

readily  distinguishable  in  the 
bark  of  young  shoots,  grow  in- 
dependently ;  each  by  the  addi- 
tion of  new  cells  to  its  inner 
face,  so  long  as  it  grows  at  all. 
The  green  layer  does  not  in- 
crease at  all  after  the  first  year 
or  two;  the  thickening  of  the 
opaque  corky  layer  soon  ex- 
cludes it  from  the  light ;  and  it 

gradually  perishes,  never  to  be  renewed  again.  The  corky  layer 
commonly  increases  for  a  few  years  only,  by  the  formation  of  new 

FIG.  165.  Transverse  section  of  a  minute  portion  of  Birch-bark,  the  corky  layer,  highly 
magnified ;  a,  the  firm  tabular  cella :  6,  the  delicate  thin- walled  cells  in  alternate  layers. 


THE    BARK.  127 

tabular  cells  :  occasionally  it  takes  a  remarkable  development, 
the  cells  swell  out  into  polyhedral  shapes,  and  multiply  with  un- 
usual rapidity  and  in  great  quantities,  forming  the  substance  called 
Cork^  as  in  the  Cork-Oak.  A  similar  growth  occurs  on  the  bark  of 
several  species  of  Elm,  of  our  Liquidambar  or  Sweet-Gum,  &c., 
producing  thick  corky  plates  on  the  branches.  In  the  Birch,  thin 
annual  layers,  of  very  durable  nature,  are  formed  for  a  great  num- 
ber of  years :  each  layer  of  tabular,  firmly  coherent  cells  (Fig. 
165,  a)  alternates  with  a  thinner  stratum  of  delicate,  somewhat  cu- 
bical and  less  compact  cells  (Z>),  which  separate  into  a  fine  powder 
when  disturbed,  and  allow  the  thin,  paper-like  plates  to  exfoliate. 

214.  The  liber,  or  inner  bark  (198),  continues  to  grow  through- 
out the  life  of  the  tree,  by  an  annual  addition  from  the  cambium- 
layer  applied  to  its  inner  surface.  Sometimes  the  growth  is  plain- 
ly distinguishable  into  layers,  corresponding  with  the  annual  layers 
of  the  wood  :  often,  there  is  scarcely  any  trace  of  such  layers  to 
be  discerned.  The  liber  of  the  Bass-wood  or  Linden,  and  of 
other  trees  and  shrubs  with  an  evidently  fibrous  bark,  consists  of 
alternate  strata  of  bast-cells  *  (or  of  parenchyma  abounding  with 
bundles  of  bast-cells)  and  of  parenchyma  alone.  In  the  Sugar 
Maple,  only  a  small  proportion  of  bast-cells  are  formed  after  the 
first  year.  In  Negundo  there  is  a  fine  deposit  of  bast-cells  the 
first  year  (Fig.  159,  well  distinguished  by  their  opaline  appearance 
in  the  magnified  cross-section),  but  they  are  not  again  repeated, 
and  the  liber  ever  after  consists  of  parenchyma  alone,  or  with 
some  thin  and  short  prose nchymatous  cells  intermixed.  The  brit- 
tle liber  of  the  Beech  is  nearly  destitute  of  bast-cells.  So  is 
that  of  the  Birch ;  but  it  abounds  with  clusters  of  solidified  cells, 
which  take  their  place,  and  exactly  imitate  ordinary  bast-cells  on 
the  cross-section  (Fig.  18) ;  but  a  longitudinal  section  exhibits  the 
same  appearance,  showing  that  they  are  globular  in  shape.  In 
the  first  year's  growth  of  the  stem  of  Menispermum  Canadense, 
there  is  a  broad  arc  of  bast-cells  immediately  before  each  wedge 
of  wood  ;  in  a  stem  of  two  or  three  years  this  is  carried  away  from 
the  wood  by  the  development  of  purely  cellular  bark  from  the  in- 

*  The  name,  liher^  is  applied,  even  by  the  same  author,  sometimes  to  the 
whole  inner  bark,  of  whatever  structure,  sometimes  to  its  bast-cells  alone.  It 
is  applied  in  this  work  to  the  inner  bark  which  grows  year  after  year  from  the 
cambium-layer,  (that  is,  to  all  within  the  green  layer,}  whether  it  continues  to 
produce  bast-cells  or  not. 


128  THE    STEM. 

terposed  cambium-layer,  it  is  finally  thrown  off  at  the  surface,  and 
no  more  is  ever  formed.  A  singular  anomaly  occurs  in  a  species 
of  Cocculus,  where  Decaisne  has  shown  that  the  bast-cells  remain 
connected  with  the  face  of  the  wood,  and  are  covered  by  its  sec- 
ond layer,  so  as  eventually  to  be  found  in  the  interior  of  the 
wood.  Laticiferous  vessels  or  canals  (63)  abound  in  the  newer 
parts  of  the  liber. 

215.  Sometimes  thin  plates  of  delicate  cells,  like  those  of  cork, 
are  formed  in  the  liber  alternately  with  its  proper  tissue ;  these 
early  give  way  in  the  external  layers,  so  that  the  outer  part  of  the 
liber,  as  it  grows  older,  scales  off  in  plates  year  after  year ;  as  is 
strikingly  the  case  in  the  Buttonwood  or  Plane-tree,  in  the  Shell- 
bark  Hickory,  in  the  Larch,  Pine,  &c.  Even  the  liber  of  only 
one  or  two  years  old  is  thus  annually  detached  in  membranous 
layers  or  fibrous  shreds  from  the  stems  of  the  Currant  and  Honey- 
suckle, the  Spiraea  opulifolia  or  Nine-Bark,  and  most  strikingly  in 
the  Grape-vine.  In  the  latter  cases,  the  green  and  the  corky  lay- 
ers are  thrown  off  the  first  or  second  year ;  in  other  cases,  they 
disappear  at  a  later  period. 

216.  Obviously  the  recent  liber  and  the  newer  layers  of  wood, 
with  the  interposed  cambium-layer,  are  alone  concerned  in  the 
life  and  growth  of  the  tree.  The  old  bark  is  constantly  decaying 
or  falling  away  from  the  surface,  without  any  injury  to  the  tree ; 
while  the  heart-wood  may  equally  decay  within  without  harm,  ex- 
cept by  mechanically  impairing  the  strength  of  the  trunk. 

217.  The  crude  sap  rises  to  the  leaves  principally  through  the 
newer  wood  (210).  The  elaborated  sap  (79)  is  returned  into  the 
newest  bark,  thence  sent  to  the  cambium-layer,  and  horizontally 
diffused  through  the  medullary  rays  (which  may  be  viewed  as  in- 
ward extensions  of  the  bark)  into  the  sap-wood  and  all  other  liv- 
ing parts. 

218.  The  proper  juices  and  peculiar  products  of  plants  (80)  are 
accordingly  elaborated  in  the  foliage  and  the  bark,  especially  in 
the  latter.  In  the  bark,  therefore,  medicinal  and  other  principles 
are  usually  to  be  sought,  rather  than  in  the  wood.  Nevertheless, 
as  the  wood  is  kept  in  connection  with  the  bark  through  the  medul- 
lary rays,  many  products  which  probably  originate  in  the  former 
are  found  in  the  wood. 

219.  Exogenous  plants  almost  always  develope  axillary  buds, 
and  produce  branches  :  hence  their  stems  and  branches  gradually 
taper  upwards,  or  are  conical. 


ENDOGENOUS    STRUCTURE. 


129 


Sect.  VI.     The  Endogenous  or  Monocotyledonous  Stem. 

220.  A  cursory  notice  must  now  be  taken  of  the  stem  of  Endo- 
gens  (or  Inside-growers),  a, great  class  of  plants,  which,  although 
they  have  many  humble  representatives  in  northern  climes,  yet 
only  attain  their  full 
characteristic  devel- 
opment, and  display 
their  noble  arbores- 
cent forms,  under  a 
tropical  sun.  Yet 
Palms  —  the  type  of 
the  class  —  do  ex- 
tend as  far  north  in 
this  country  as  the 
coast  of  North  Caro- 
lina (the  natural  lim- 
it of  the  Palmetto, 
Fig.  166);  while  in 
Europe  the  Date  and 
the  Chamserops  have 
found  their  way  to 
the  warmer  parts  of 
the  European  shore 
of  the  Mediterrane- 
an. The 
manner  of 
their  growth 
gives  them 
a  striking 
appearance; 
their  trunks 

being  unbranched  cylindrical  columns,  rising  majestically  to  the 
height  of  from  thirty  to  one  hundred  and  fifty  feet,  and  crowned  at 
the  summit  with  an  ample  plume  of  peculiar  foliage.  Their  inter- 
nal structure  is  equally  different  from  that  of  ordinary  wood. 

221.  The  stem  of  an  Endogen,  as  already  remarked  (185), 
offers  no  manifest  distinction  into  bark,  pith,  and  wood  ;  and  the 
latter  is  not  composed  of  concentric  rings  or  layers,  nor  traversed 

FIG.  166.    The  Chameerops  Palmetto,  in  various  stages,  and  the  Yucca  Draconis. 


130 


THE    STEM. 


by  medullary  rays.  But  it  consists  of  bundles  of  woody  and  vas- 
cular tissue,  in  the  form  of  thick  fibres  or  threads,  which  are  im- 
bedded, with  little  apparent  regularity,  in  cellular  tissue ;  and  the 
whole  is  inclosed  in  an  integument  which  does  not  strictly  resemble 
the  bark  of  an  Exogenous  plant ;  inasmuch  as  it  does  not  increase 
by  layers,  and  is  never  separable  from  the  wood.  The  fibrous 
bundles  which  compose  the  wood,  and  which  consist  of  a  mass  of 
woody  fibres  surrounding  several  vessels,  are  distributed  through- 
out the  cellular  system  of  the  stem,  most  copiously  near  the  cir- 
cumference, but  without  being  arranged  in  layers.  Each  bundle 
usually  contains  all  the  elements  of  the  wood  of  the  exogenous 
stem,  namely,  vessels,  proper  woody  tissue,  and  bast-cells.  The 
bundles  may  be  traced  directly  from  the  base  of  the  leaves  down 
through  the  stem,  some  of  them  to  the  roots  in  a  young  plant,  while 
others,  curving  outwards,  lose  themselves  in  the  cortical  integu- 
ment, or  rind.  As  the  stem  increases,  new  bundles,  springing 
from  the  bases  of  more  recently  developed  leaves,  are  at  first  di- 
rected towards  the  centre  of  the  stem,  along  which  they  descend 
for  a  considerable  distance,  then,  curving  outwards,  they  mostly 
terminate  in  the  rind.  It  is  partly  in  consequence  of  the  cohesion 
of  these  obliquely  descending  fibres  to  the  false  bark,  that  the  lat- 
ter cannot,  as  in  Exogens,  be  separated  from  the  wood  beneath. 
The  manner  in  which  the  woody  threads  are  consequently  interwo- 
ven is  shown  in  Fig.  167.  The  palm- 
like Yuccas  of  the  Southern  States  offer 
beautiful  illustrations  of  the  kind.  The 
appearance  on  a  cross-section  of  an  en- 
dogenous stem  is  shown  in  Fig.  150. 
The  new  woody  bundles  which  are  add- 
ed from  year  to  year,  instead  of  ar- 
ranging themselve  outside  the  earlier 
wood  and  inclosing  it,  as  in  Exogens, 
actually  descend  more  in  the  centre,  and 
gradually  force  outward  those  which 
were  first  formed.  Such  a  stem,  there- 
fore, instead  of  having  the  oldest  and 
hardest  wood  at  the  centre  and  the  new- 
est and  softest  at  the  circumference,  as  in  ordinary  trees,  is  sof\est 


FIG.  167.    Vertical  and  transverse  section  of  a  young  endogenous  stem,  to  show  the  curv- 
ing of  the  fibres. 


ORIGIN    OF    THE    WOOD.  131 

towards  the  centre  and  most  compact  at  the  circumference.  In 
this  way,  and  by  the  general  growth  of  the  cellular  tissue  in  which 
the  fibre- vascular  bundles  are  imbedded,  the  stem  increases  in  di- 
ameter as  long  as  the  rind  is  capable  of  distention.  In  some  in- 
stances, as  in  the  arborescent  Yuccas  and  the  Dracsenas  or  Dragon- 
trees,  the  rind  remains  soft  and  capable  of  unlimited  expansion ; 
and  the  woody  bundles  descend  after  having  reached  the  circum- 
ference, and  thus  the  older  stems  continue^  to  increase  in  diameter, 
much  after  the  manner  of  an  Exogen  ;  but  in  the  Palms,  and  in 
most  woody  Endogens,  it  soon  indurates,  and  the  stem  consequent- 
ly increases  no  further  in  diameter.  The  wood  of  the  lower  part 
of  such  stems  is  more  compact  than  the  upper,  being  more  filled 
with  woody  bundles,  the  cells  of  which  are  lignified  by  internal 
deposition ;  and  the  rind  is  harder,  from  the  greater  number  of  lig- 
neous fibres  which  terminate  in  it,  and  from  its  proper  induration. 
Further  increase  in  diameter  being  in  these  cases  impossible,  and 
the  lower  part  of  the  stem  becoming  at  length  choked  up  by  the 
multitude  of  descending  bundles,  it  appears  that  the  life  of  such 
Endogens  must  be  limited. 

222.  Palms  generally  grow  from  the  terminal  bud  alone,  and 
perish  if  this  bud  be  destroyed ;  the  foliage  is  also  borne  in  a  clus- 
ter at  the  summit  of  the  trunk  ;  which  consequently  forms  a  simple 
cylindrical  column.  But  in  some  instances  two  or  more  buds  de- 
velope,  and  the  stem  branches,  as  in  the  Doum-Palm  of  Upper 
Egypt,  and  in  the  Pandanus,  or  Screw-Pine  (Fig.  117),  which 
belongs  to  a  family  closely  allied  to  Palms :  in  such  cases  the 
branches  are  cylindrical.  But  when  lateral  buds  are  freely  devel- 
oped (as  in  the  Asparagus),  or  the  leaves  are  scattered  along  the 
stem  or  branches  (as  in  the  Bamboo,  Maize,  &c.),  these  taper  up- 
wards, just  as  in  Exogens. 

223.  Grasses  have  endogenous  stems,  mostly  of  annual  dura- 
tion, and  which  early  become  hollow  in  the  manner  already  indi- 
cated (193).  In  several  of  them,  such  as  the  Maize  and  Sugar- 
Cane,  the  stem  remains  solid  ;  and  these  furnish  good  examples  of 
ordinary  endogenous  structure. 

Sect.  VII.     Of  the  Theoretical  Structure  of  the  Stem,  etc. 

224.  Origin  of  the  Wood,  &C.  We  have  seen  that  the  plantlet 
which  has  as  yet  developed  only  one  internode  and  one  leaf  (188), 


132  THE    STEM. 

or  one  pair  of  leaves  in  germination  (118),  is  complete  in  its  parts, 
being  provided  with  all  the  organs  of  vegetation,  namely  with  root, 
stem,  and  foliage.  By  this  time  its  layer  of  wood  is  also  manifest 
(a  few  vessels  being  first  developed  in  four  or  more  clusters, 
around  which,  principeilly  on  the  outer  side,  woody  tissue  at  once 
begins  to  appear)  ;  and  the  bark  a  little  later  exhibits  traces  of  the 
elements  of  its  three  layers.  This  nascent  wood  begins  to  form 
early  in  germination.  In  a  large  and  highly  developed  embryo  it 
exists  before  germination.  The  conversion  of  young  cells  of  pa- 
renchyma into  vessels  and  wood-cells  either  commences  in  the 
radicle  or  stem-part  and  extends  upwards  into  the  cotyledons,  when 
the  latter  are  proportionally  little  developed  ;  or,  when  they  are 
large  in  proportion  (as  in  the  Almond,  Fig.  97),  it  commences  in 
the  cotyledons  and  grows  downwards  into  the  radicle.  The  wood 
of  the  rudimentary  stem  and  that  of  the  leaf  or  leaves  it  bears  are 
therefore  in  connection,  are  parts  of  the  same  system.  As  the 
root  is  produced  from  the  lower  end  of  the  radicle  (Fig.  107),  its 
forming  woody  tissue  extends  downwards  into  it  (the  primary  ves- 
sels, however,  commonly  developing  as  ducts  instead  of  spiral  ves- 
sels), and  grow  on  as  that  advances  by  its  cellular  growth.  The 
leaf  or  pair  of  leaves  of  the  second  internode  by  this  time  begins 
to  appear ;  in  which,  or  at  the  base  of  vvhich,  new  vascular  and 
woody  tissues  originate  in  the  same  way,  extending  through  the 
leaf  to  form  its  woody  system,  o"r  framework,  making  the  woody 
stratum  in  the  second  internode  of  stem  as  it  lengthens,  and 
then  contributing  to  the  increase  of  the  wood  of  the  parent  inter- 
node beneath.  This  is  repeated  throughout  the  whole  growth 
of  the  season ;  each  internode  forming  its  own  woody  system,  a 
portion  of  which  appears  separately  in  the  leaf,  while  that  in  its 
stem  blends  with  that  of  the  internodes  below  to  form  the  gen- 
eral zone  of  wood,  in  the  exogenous  stem.  It  is  nearly  the 
same  in  the  endogenous  stem,  except  that  the  wood  forms  in  sep- 
arate bundles  or  threads,  and  these  are  commingled  through  the 
whole  circumference  of  the  young  stem,  instead  of  the  new  wood 
being  constantly  applied  to  the  outside  of  that  which  was  first 
formed.  In  the  endogenous  stem,  the  individual  threads  or  bun- 
dles which  form  the  wood  may  often  be  separately  traced  from 
the  base  of  the  leaf  to  their  termination,  at  a  considerable  distance 
below.  In  the  exogenous  stem,  their  elements  are  usually  conflu- 
ent and  undistinguishable  in  the  common  layer. 


ORIGIN    OF    THE    WOOD.  133 

225.  That  the  wood  thus  originates  in  connection  with  the  leaves 
is  shown,  —  (1.)  By  tracing  the  threads  of  soft  woody  Endogens, 
such  as  Yucca,  and  some  Palms,  directly  from  the  base  of  the  leaf 
into  the  stem,  and  thence  downward  to  their  termination,  towards 
which  they  become  attenuated,  lose  their  vessels,  and  are  finally 
reduced  to  slender  shreds  of  woody  tissue.  (2.)  Because  the 
amount  of  wood  formed  in  a  stem  or  branch  is  in  proportion  to 
the  number  and  size  of  the  leaves  it  bears ;  its  amount  in  any  por- 
tion of  the  branch  is  in  direct  proportion  to  the  number  of  leaves 
above  that  portion.  Thus,  when  the  leaves  are  distributed  along  a 
branch,  it  tapers  to  the  summit,  as  in  a  common  Reed  or  a  stalk  of 
Indian  Corn ;  when  they  grow  in  a  cluster  at  the  apex,  it  remains 
cylindrical,  as  in  a  Palm  (Fig.  166).  Consequently  the  aggregate 
diameter  of  the  branches  is  (cceteris  paribus)  equal  to  that  of  the 
trunk  from  which  they  arise ;  as  is  beautifully  illustrated  by  the 
excurrent  stem  of  Pines  and  Firs,  (carried  directly  upwards  by  the 
continued  growth  of  the  leading  shoot,  155,)  the  diameter  of  which 
regularly  diminishes  as  the  lateral  branches  are  given  off.  Conse- 
quently the  increase  of  the  trunk  in  diameter  directly  corresponds 
with  the  number  and  vigor  of  the  branches.  The  greater  the  de- 
velopment of  vigorous  branches  on  a  particular  side  of  a  tree,  the 
more  wood  is  formed  and  the  greater  the  thickness  of  the  annual 
layers  on  that  side  of  the  trunk.  (3.)  In  a  seedling,  the  wood  ap- 
pears just  in  proportion  as  the  leaves  are  developed.  (4.)  If  a 
young  branch  be  cut  off  just  below  a  node  (141),  so  as  to  leave  an 
internode  without  leaves  or  bud,  no  increase  in  diameter  will  take 
place  down  to  the  first  leaf  below.  But  if  a  bud  be  inserted  into 
or  ingrafted  upon  this  naked  internode,  as  the  bud  developes, 
increase,  in  diameter,  with  the  formation  of  new  wood,  recom- 
mences. 

226.  These  facts  conspire  to  show,  not  only  the  general  depend- 
ence of  the  wood  on  the  leaves  for  its  formation,  but  also  that  the 
wood  is  produced  from  above  downwards.*  The  following  are 
some  of  the  considerations  that  may  be  adduced  in  confirmation  of 
this  view  :  —  (1.)  When  a  ligature  is  closely  bound  around  a  grow- 


*  There  is  an  article  by  James  Warren,  in  the  first  volume  of  the  Memoirs 
of  the  American  Academy  of  Arts  and  Sciences,  published  in  1785,  ingen- 
iously maintaining  the  downward  growth  of  the  wood,  apparently  from  orig- 
inal observations  altogether. 
12 


134  THE    STEM. 

ing  exogenous  stem,  the  part  above  the  ligature  swells ;  that  below 
does  not.  Every  one  may  have  observed  the  distortions  that  twin- 
ing stems  thus  accidentally  produce  upon  woody  exogenous  trunks. 
On  examination,  the  woody  fibres  are  found  to  be  arrested  at  the 
upper  margin  of  the  ligature,  and  thrown  into  curved  and  knotted 
forms ;  or,  where  the  ligature  is  spiral,  the  descending  fibres  fol- 
low the  course  of  the  obstruction.  (2.)  When  we  girdle  an  exoge- 
nous stem,  by  removing  a  ring  of  bark  so  as  completely  to  ex- 
pose the  surface  of  the  wood,  the  part  above  the  ring  enlarges  in 
the  same  manner ;  that  below  does  not,  except  by  the  granulation 
of  cellular  tissue,  until  the  incision  is  healed.  (3.)  In  a  graft,  the 
descending  wood  of  the  scion  may  often  be  seen  to  be  quite  dis- 
tinct from  the  stock ;  the  latter  sometimes  dies  while  the  scion 
continues  to  grow.  (4.)  In  many  cases  the  fibres  of  wood  are 
found  to  curve  abruptly  round  a  projection,  gradually  resuming 
their  perpendicular  direction  below.  Sometimes  they  take  a  very 
sinuous  course,  when  there  is  no  obstruction  or  evident  cause 
of  disturbance  ;  the  fibres  of  adjacent  layers  even  crossing  each 
other  at  right  angles,  showing  an  entire  independence  of  the  ante- 
cedent layer  in  their  growth.  (5.)  The  wood  of  the  roots  is  ad- 
mitted to  grow  in  a  descending  direction.  But  it  is  continuous 
with  that  of  the  stem  ;  and  its  first  layer,  the  extension  of  the 
wood  of  the  radicle  into  the  primary  root,  agrees  in  composition 
with  the  wood  of  the  succeeding  layers  in  the  stem,  having  no 
spiral  vessels,  but  only  ducts. 

227.  We  have  seen  (148)  that  lateral  buds  develope  into  branch- 
es, just  as  the  original  embryo  developed  into  the  primary  stem. 
Now  the  original  embryo,  or  primary  bud  (144),  not  only  grew  up- 
wards to  form  the  stem,  but  downwards  to  form  the  root.  Buds 
grow  upwards  into  branches ;  have  they  aught  corresponding  to 
the  downward  growth  which  in  the  original  stem  is  represented  by 
the  roots  ?  The  answer  is  furnished  by  those  buds  which  may  be 
made  to  grow  independently  of  the  parent  stem ;  such,  for  in- 
stance, as  the  bulblets  of  the  Tiger  Lily  (Fig.  143),  which  are 
merely  axillary  buds  with  fleshy  scales,  and  which,  when  they  fall 
to  the  ground,  or  even  while  yet  in  their  native  situation,  emit 
rootlets  from  their  base,  whose  downward  growth  is  the  counterpart 
of  the  upward  growth  of  the  stem  to  which  the  bud  gives  rise. 
The  same  evidence  is  furnished  by  those  ordinary  buds  which  nat- 
urally grow  in  union  with  the  parent,  but  which  the  gardener 


ITS    THEORETICAL    STRUCTURE.  135 

transfers  to  the  soil  in  the  form  of  cuttings  (which  are  merely  buds 
with  a  small  piece  of  the  stem),  where  they  throw  out  roots  from 
the  base  and  grow  into  independent  plants.  As  the  bud,  excited 
by  warmth  and  moisture,  developes  upwards  into  a  stem,  just  as  it 
would  have  done  into  a  branch  had  it  remained  in  union  with  the 
parent,  so  it  strikes  root  downward  from  the  base  of  the  cutting, 
and  the  woody  fibres  of  these  roots,  taken  together,  may  be  traced 
back  directly  to  the  bud.  Evidently  the  fibres,  which  may  be 
traced  as  wood  from  the  bud  down  to  the  base  of  the  cutting,  are 
prolonged  beyond  into  roots.  The  resemblance  between  the  orig- 
inal stem  and  the  branches  it  bears,  therefore,  holds  good  through- 
out. As  the  downward  growth  of  the  original  stem  gives  rise  to 
roots,  so  the  downward  growth  of  the  lateral  buds,  when  they  grow 
in  connection  with  the  parent  stem,  contributes  to  the  wood  be- 
neath, and  at  length  to  the  roots.  In  layering  (167),  the  gardener 
well  knows  that  roots  strike  more  readily  when  an  incision  is  made 
into  the  stem  where  it  is  covered  with  the  soil.  The  evident  ex- 
planation is,  that  the  descending  woody  growth,  arrested  by  the 
incision  in  the  cellular  callus  that  forms  there,  is  forced,  as  it 
were,  to  strike  at  once  into  the  soil,  instead  of  pursuing  the  longer 
course  through  the  main  trunk  to  the  same  ultimate  destination. 
This  is  the  very  economy  of  shrubs  and  trees  which  naturally 
multiply  by  suckers  and  stolons ;  from  which  the  singular  Ban- 
yan (Fig.  119),  that  in  time  spreads  into  a  grove, 

"  High  over-arched,  with  echoing  walks  between," 

in  no  wise  differs,  except  that  the  roots  strike  and  the  whole  pro- 
cess goes  on  high  in  the  open  air.  In  this  case,  portions  of  the 
new  wood  merely  take  another  and  nearer  course  to  the  ground  in 
the  form  of  aerial  roots,  which  in  time  produce  additional  trunks, 
instead  of  continuing  their  adhesion  to  the  branches,  and  contribut- 
ing to  the  increase  in  diameter  of  the  main  trunk.  The  additional 
trunks  thus  produced,  and  which  eventually,  by  separation  and 
the  decay  of  the  original  trunk,  may  form  the  stems  of  independ- 
ent trees,  exactly  represent  the  outer  and  newer  layers  of  an  ordi- 
nary tree,  the  main  stem  representing  the  old  and  often  decay- 
ing centre.  Further  and  very  striking  illustrations  are  furnished 
by  those  curious  stems  of  Barbacenia,  Kingia,  and  some  Lycopo- 
dia,  in  which  numerous  aerial  roots,  instead  of  striking  off  free 
from  the  exterior,  descend  under  the  bark  or  rind,  where  they  are 


136  THE    STEM. 

closely  pressed  together,  and  form,  as  it  were,  coarse  threads  of 
wood ;  but  on  reaching  the  ground  they  assume  the  appearance 
and  functions  of  real  roots.  Every  transition  is  found  between 
this  arrangement  and  that  in  which  they  are  united  and  blended 
with  one  another  in  a  continuous  ligneous  tissue. 

228.  Nevertheless,  it  is  carrying  such  conclusions  much  too  far 
to  assert,  with  Thouars  and  Gaudichaud,  that  wood  is  the  roots 
of  buds  or  of  leaves,  and  to  insist  that  each  branchlet  or  branch 
contributes  a  distinguishable  or  definite  portion  to  the  trunk  below, 
which  is  prolonged  into  a  particular  root  or  set  of  roots.  In  Palms, 
indeed,  according  to  the  high  authority  of  Martius,  there  are  no 
other  threads  of  wood  in  the  trunk  than  those  which  have  proceed- 
ed from  the  bases  of  the  leaves.  But  in  exogenous  stems,  —  of 
which  most  is  known,  —  although  the  principal  growth  commences 
and  proceeds  in  the  manner  above  described  (224),  yet  it  undoubt- 
edly goes  on  from  year  to  year  by  the  continual  multiplication  and 
growth  of  cells  (32,  203-205)  over  the  whole  extent  of  the  cam- 
bium-layer nearly  simultaneously,  irrespective,  at  least  in  the  trunk 
and  roots,  of  any  direct  connection  with  buds  or  leaves  above.  The 
formation  of  wood  is  resumed  each  spring  where  it  was  interrupted 
the  previous  autumn.  This  is  shown  in  the  case  of  stumps  which 
have  been  kept  alive  for  several  years,  in  consequence  of  the  natu- 
ral ingrafting  of  some  of  their  roots  with  the  roots  of  adjacent  trees 
of  the  same  species,  and  which  have  continued  to  form  annual  lay- 
ers, although  very  thin  ones,  while  they  survived,  notwithstanding 
they  bore  no  leafy  shoots,  or  scarcely  any.*  The  cambium-layer, 
however  it  may  have  originated  in  the  first  instance,  blends  into  a 
common  stratum,  which  appears  to  possess  an  inherent  power  of 
continuing  and  reproducing  itself,  while  it  is  nourished  by  the 
elaborated  sap,  which  is  generally  supplied  by  the  foliage  above. 
It  is  well  known  that  the  ascending  sap  is  laterally  diffused  with 
great  readiness  through  the  whole  circumference  of  the  sap-wood  ; 
if  this  be  destroyed  on  one  side  of  the  tree,  the  sap  that  ascends  on 
the  other  is  equably  supplied  to  all  the  branches  throughout.  The 
branches  of  each  year's  growth  are,  therefore,  kept  in  fresh  com- 


*  The  ascertained  fact,  that  the  fibro-vascular  tissue  of  secondary  roots  orig- 
inates independently  in  the  parenchyma,  adjacent  to,  but  not  at  first  in  con- 
tact with,  the  wood  of  the  stem,  is  decisive  against  the  Thouarsian  hypothesis, 
as  strictly  carried  out. 


ITS  COMPOSITE  NATURE.  137 

munication,  by  means  of  the  newer  layers  of  wood,  with  the  fresh 
rootlets,  which  are  alone  active  in  absorbing  the  crude  food  of  the 
plant  from  the  soil.  The  fluid  they  absorb  is  thus  conveyed  direct- 
ly to  the  branches  of  the  season,  which  alone  develope  leaves  to 
digest  it.  And  the  food  they  receive,  having  been  elaborated  and 
converted  into  organic  nourishing  matter,  is  partly  expended  in  the 
upward  growth  of  new  branches,  and  partly  in  the  downward  for- 
mation of  a  new  layer  of  wood,  reaching  from  the  highest  leaves 
to  the  remotest  rootlets.  These  two  essential  organs,  namely,  the 
rootlets  which  absorb,  and  the  leaves  which  digest,  the  plant's 
nourishment,  are,  therefore,  annually  renewed ;  and,  whatever 
their  distance  or  the  age  of  the  tree,  are  maintained  in  fresh  com- 
munication through  the  new  annual  layers.  As  the  exogenous 
tree,  therefore,  annually  renews  its  buds  and  leaves,  its  wood, 
bark,  and  roots,  —  every  thing,  indeed,  that  is  concerned  in  its  life 
and  growth,-^ there  seems  to  be  no  reason,  no  necessary  cause  in- 
herent in  the  tree  itself,  why  it  should  not  live  indefinitely.  Ac- 
cordingly, several  trees  are  known  to  have  lived  for  a  thousand 
years  or  more ;  and  others  are  now  living  which  are  with  high 
probability  thought  to  be  above  two  thousand  years  old.*  This 
longevity,  however,  will  not  appear  surprising  when  we  remember 
that 

229.  The  Plant  is  a  Composite  Being,  or  community,  lasting,  in 

the  case  of  a  tree  especially,  through  an  indefinite  and  often  im- 
mense number  of  generations.  These  are  successively  produced, 
enjoy  their  term  of  existence,  and  perish  in  their  turn.  Life  passes 
onward  continually  from  the  older  to  the  newer  parts,  and  death 
follows,  with  equal  step,  at  a  narrow  interval ;  no  portion  of  the 
tree  is  now  living  that  was  alive  a  few  years  ago ;  the  leaves  die 
annually  and  are  cast  off",  while  the  internodes  or  joints  of  stem  that 
bore  them,  as  to  their  wood  at  least,  are  buried  deep  in  the  trunk, 
under  the  wood  of  succeeding  generations ;  converted  into  heart- 
wood  they  are  equally  lifeless,  or  perchance  decayed,  while  the 
bark  that  belonged  to  them  is  in  time  thrown  off*  from  the  surface. 


*  The  subject  of  the  longevity  of  trees  has  been  ably  discussed  by  De  Can- 
dolle,  in  the  BihliotHque  Universelle  of  Geneva,  for  May,  1831,  and  in  the 
second  volume  of  his  Physiologie  V6g6tale:  also,  more  recently,  by  Prof  Al- 
phonse  De  Candolle.  In  this  country,  an  article  on  the  subject  has  appeared 
in  the  North  American  Review,  for  July,  1844. 
12* 


138  THE    STEM. 

It  is  the  aggregate,  the  blended  mass  alone,  that  long  survives. 
Plants  of  single  cells  are  alone  perfectly  simple,  and  their  exist- 
ence is  extremely  short.  But  the  more  complex  vegetable  of  a 
higher  grade  is  not  to  be  compared  with  the  animal  of  the  highest 
organization,  where  the  offspring  always  separates  from  the  parent, 
and  the  individual  is  consequently  simple  and  indivisible  ;  while  it 
is  truly  similar  to  the  branching  of  arborescent  coral,  or  other 
compound  animals  of  the  lowest  grade,  where  successive  genera- 
tions, though  capable  of  living  independently  and  sometimes  sepa- 
rating spontaneously,  yet  are  usually  developed  in  connection, 
blended  in  a  general  body,  and  nourished  more  or  less  in  common. 
Thus  the  coral  structure  is  built  up  by  the  combined  labors  of  a 
vast  number  of  individuals,  —  by  the  successive  labors  of  a  great 
number  of  generations.  The  surface  or  the  recent  shoots  alone 
are  alive  ;  and  here  life  is  superficial,  all  underneath  consisting  of 
the  dead  remains  of  former  generations.  The  arborescent  species 
are  not  only  lifeless  along  the  central  axis,  but  are  dead  through- 
out towards  the  bottom :  as,  in  a  genealogical  tree,  only  the  later 
ramifications  are  among  the  living.  It  is  the  same  with  the  tree, 
except  that,  as  the  plant  imbibes  its  nourishment  principally  from 
the  soil  through  its  roots,  it  makes  a  downward  growth  also,  and, 
by  constant  renewal  of  fresh  tissues  (216,  228)  maintains  the  com- 
munication between  the  two  growing  extremities,  the  buds  and  the 
rootlets.  We  have  seen  that  branches  grow  from  the  parent  stem 
just  as  this  grew  from  the  embryo,  only  that  they  are  implanted  on 
the  main  trunk  instead  of  the  ground ;  still  they  are  capable  of 
living  as  independent  individuals,  and  often  do  in  various  ways  (as 
by  bulbs,  tubers,  layers,  stolons,  offsets,  &c.)  spontaneously  ac- 
quire a  separate  existence.  The  branches,  therefore,  or  the  buds, 
which  are  the  branches  in  an  earlier  stage,  are  real  individuals, 
which  conspire  to  make  up  the  composite  tree.  The  contrary 
view  would  lead  to  the  absurdity  of  an  individual  consisting  of  sev- 
eral genera  and  species ;  since  the  Apple,  Pear,  Mountain  Ash, 
Quince,  Medlar,  and  Hawthorn  may  all,  by  ingrafting,  be  com- 
bined in  a  single  tree.  It  would  also  oblige  us  to  consider  as  a 
single  individual  all  the  plants  which  have  arisen  from  the  mechan- 
ical subdivision  of  an  original  stem,  —  for  example,  perhaps  all  the 
Lombardy  Poplars  in  this  country,  or  even  a  large  part  of  the  Po- 
tatoes of  Europe  and  America.  While  actually  united,  however, 
all  the  branches  are  to  some  extent  subordinate  to  the  general- 


PHYTONS. 


139 


/ 


whole  ;  so  that  the  term  individual  plant  is  justly  applied  to  the  ag- 
gregate stem  and  branches  while  they  remain  united,  but  no  longer. 

230.  Phytons.  The  analysis  of  the  Phsenogamous  plant  must  be 
carried  still  further :  for  a  branch,  or  the  simple  primary  stem  it- 
self, is  composed  of  a  lineal  succession  of  similar  parts,  developed 
one  upon  the  summit  of  another,  each  produced  by  the  preceding, 
and  producing  that  which  in  turn  surmounts  it  (143) ;  that  is,  it 
consists  of  a  series  of  individual  plantlets  or  plant-elements^  which 
by  their  repetition  make  up  the  vegetable  body.  The  first  of 
these  preexists  in  the  seed,  as  the  embryo, 

or  initial  plantlet  (Fig.  105) :  the  down- 
ward growth  from  its  lower  extremity 
forms  the  root  (Fig.  107),  while  from 
above  it  gives  birth  to  all  the  rest,  in  lin- 
eal succession.  A  name  being  needful  by 
which  to  designate  this  potential  plant,  the 
repetition  of  which  makes  up  the  perfect 
vegetable,  that  of  Phyton  (from  the 
Greek  (f)VT6v,  a  plant)  has  been  adopted 
for  the  purpose. 

231.  The  dicotyledonous  embryo  (Fig. 
100,  105)  is  a  double  organ,  or  consists  of 
two  simple  phytons,  with  their  stem-por- 
tions united  side  by  side  to  form  the  radi- 
cle, but  each  with  its  own  leaf  or  cotyle- 
don. The  monocotyledonous  embryo  is 
equivalent  to  half  the  dicotyledonous,  and 
therefore  exhibits  the  simplest  case.  It 
developes  one  primary  phyton  in  germi- 
nation (Fig.  168,  a),  this  a  second  (b), 
this  a  third  (c),  and  so  on  ;  each  like  the 
preceding,  only  successively  larger  and 
more  vigorous  as  the  plant  thus  multiplies 
its  organs ;  except  that  the  primary  one 
alone  grows  downwards  into  a  root  in  the 
first  instance.  But  the  others  mingle  their 
woody  tissues  with  those  of  the  older  phy- 
tons beneath,  and  thus  draw  up  their  portion  of  the  liquid  which 


FIG.  163.     Diagram  to  illustrate  the  development  of  a  Monocotyledonous  plant,  by  super- 
posed phytons;  a-g,  the  successive  phytons,  beginning  with  the  first. 


140 


THE    LEAVES. 


the  primary  root  imbibes.  They  are  likewise  apt  to  send  forth 
secondary  roots  of  their  own,  to  establish  a  di- 
rect communication  with  the  soil  (as  in  Fig. 
168,  b).  This  they  uniformly  do  when  in  con- 
tact with  the  soil  (130),  and  not  rarely  when 
raised  to  some  distance  above  it  (131) :  or  they 
may  be  made  to  strike  root  and  live  independ- 
ently, when  taken  off  as  cuttings  (227).  When 
the  dicotyledonous  embryo  goes  on  to  develope 
double  phytons,  like  itself,  each  node  bears  a 
pair  of  leaves  (as  in  Fig.  101-104),  or,  jn 
botanical  description,  the  leaves  are  said  to  be 
opposite ;  as  they  are  in  the  Maple,  in  the  Mint 
Family,  &c.  But  quite  as  frequently  the  phy- 
tons become  disjoined  or  simple  after  the  first 
or  second,  each  bearing  a  single  leaf  only ;  so 
that  the  leaves  become  alternate,  just  as  in  those  from  the  mono- 
cotyledonous  embryo,  except  that  they  are  there  alternate  from  the 
very  first.  This  occurs  in  the  Apple,  Cherry  (Fig.  169),  and  num- 
berless other  instances. 

232.  The  same  analysis  applies  to  axillary  buds  and  branches. 
In  most  of  our  trees  and  shrubs  these  buds  acquire  considerable 
complexity  before  they  begin  to  unfold  (144),  and  then  grow 
almost  simultaneously  :  but  in  some  of  them,  as  in  most  annual 
herbs,  the  axillary  phytons  begin  to  develope  one  by  one. 


CHAPTER    V 


OF    THE    LEAVES. 


Sect.  I.     Their  Arrangement.     (Phyllotaxis,  etc.) 

233.  The  fundamental  organs  of  the  vegetable,  namely,  the 
root,  stem,  and  leaves,  are  so  intimately  associated  and  mutually 
dependent,  that  the  structure  and  office  of  no  one  of  them  can  be 
separately  treated  of.  The  stem,  in  particular,  cannot  be  under- 
stood apart  from  the  leaves.     It  has  accordingly  been  necessary  to 


FIG.  169,    Germination  of  the  Cherry  ;  the  leaves  alternata  after  the  first  pair,  or  cotyledons. 


THEIR   ARRANGEMENT.  141 

anticipate  several  of  the  leading  points  of  the  present  chapter.  As 
to  the  general  office  of  leaves  in  the  vegetable  economy,  it  has 
been  assumed  that  the  leaf  is  an  apparatus  in  which,  under  the 
agency  of  sunlight,  the  sap  is  digested,  and  converted  into  the 
proper  nourishment  of  the  plant  (79,  114).  As  to  their  situation 
upon  the  stem,  it  has  been  stated  that  they  invariably  arise  from 
the  nodes  (141),  just  below  the  point  where  buds  appear  (148). 
So  that  wherever  a  bud  or  branch  is  found,  a  leaf  exists,  or  has 
existed,  either'  in  a  perfect  or  rudimentary  state,  just  beneath  it ; 
and  buds  (and  therefore  branches),  on  the  other  hand,  are  or  may 
be  developed  in  the  axils  of  all  leaves,  and  do  not  normally  exist 
in  any  other  situation.  And  finally,  the  relation  of  leaves  to  the 
wood  and  the  general  structure  of  the  stem  has  just  been  noticed 
(224-231).  From  its  natural  connection  with  that  topic,  it  will 
be  most  convenient  first  to  consider  their  arrangement  on  the  stem. 
This  subject,  which  has  of  late  been  elaborately  investigated,  has 
received  the  name  of 

234.  Phyllotaxis  (from  two  Greek  words,  signifying  leaf-arrange- 
ment). We  can  here  only  briefly  illustrate  the  general  laws  which 
appear  to  regulate  the  arrangement  of  leaves  on  the  stem,  as  man- 
ifested in  the  several"  modes  which  are  of  ordinary  occurrence. 

235.  The  point  of  attachment  of  a  leaf  (or  other  organ)  with  the 
stem  is  termed  its  insertion. 

236.  In  botanical  descriptions,  leaves  are  said  to  be  alternate 
(149),  when  there  is  only  one  to  each  node  or  phyton,  as  in  Fig. 
168,  in  which  case  the  successive  leaves  are  thrown  alternately  to 
different  sides  of  the  stem  :  they  are  said  to  be  opposite  when  each 
node  bears  a  pair  of  leaves  (149,  231),  in  which  case  the  two 
leaves  always  diverge  from  each  other  as  widely  as  possible,  that 
is,  they  stand  on  opposite  sides  of  the  stem  and  point  in  opposite 
directions  (Fig.  107,  104),  or  else  they  are  verticillate  or  whorled, 
when  there  are  three  or  more  leaves  in  a  circle  (verticil  or  whorl) 
upon  each  node ;  in  which  case  the  several  leaves  of  the  circle  di- 
verge from  each  other  as  much  as  possible,  or  are  equably  distrib- 
uted around  the  whole  circumference  of  the  axis.  The  first  of  the 
three  is  the  simplest  as  well  as  the  commonest  method,  occurring 
as  it  does  in  almost  every  Monocotyledonous  plant  (where  it  is 
plainly  the  normal  mode.  Fig.  168),  and  in  the  larger  number  of 
Dicotyledonous  plants  likewise,  after  the  first  or  second  nodes.  It 
should  therefore  be  first  examined. 


142 


THE    LEAVES. 


237.  Alternate  Leaves.  This  general  term,  which  commonly  suf- 
fices in  descriptive  botany,  obviously  comprises  a  variety  of  modes. 
There  is,  first,  the  case  to  which  the  name  is  strictly  applicable, 
namely,  where  the  leaves  are  alternately  disposed  on  exactly  oppo- 
site sides  of  the  stem  (as  in  Fig.  168)  ;  the  second  leaf  being  thrown 
to  the  side  farthest  away  from  the  first,  while  the  third  is  equally  re- 
moved from  the  direction  of  the  second,  and  is  consequently  placed 
directly  over  the  first,  the  fourth  stands  over  the  second,  and  so  on 
throughout.  Such  leaves  are  accordingly  distichous  or  two-ranked. 
They  form  two  vertical  rows  :  on  one  side  is  the  series  1,  3,  5,  7, 
&c. ;  on  the  opposite,  the  series  2,  4,  6,  8,  and  so  on.  This  mode 
occurs  in  all  Grasses,  in  many  other  Monocotyledonous  plants,  and 
170  among  the  Dicotyledonous  in  the  Linden. 

A  second  variety  of  alternate  leaves  is 

238.  The  tristichous  or  three-ranked  ar- 
rangement, which  is  seen  in  Sedges  (Fig. 
170)  and  some  other  Monocotyledonous 
plants.  Taking  any  leaf  we  please  to  be- 
gin with,  and  numbering  it  1,  we  pass  round 
one  third  of  the  circumference  of  the  stem 
as  we  ascend  to  leaf  No.  2 ;  another  third 
of  the  circumference  brings  us  to  No.  3; 
another  brings  us  round  to  a  line  with  No. 
1,  exactly  over  which  No.  4  is  placed.  No. 
5  is  in  like  manner  over  No.  2,  and  so  on. 
They  stand, therefore,  in  three  vertical  rows, 
one  of  which  contains  the  numbers  1,  4,  7, 
10 ;  another,  2,  5,  8,  11 ;  the  third  3,  6,  9, 
12,  and  so  on.  If  we  draw  a  line  from  the 
insertion  of  one  leaf  to  that  of  the  next,  and 
so  on  to  the  third,  fourth,  and  the  rest  in 
succession,  it  will  be  perceived  that  it  winds 
around  the  stem  spirally  as  it  ascends.  In 
the  distichous  mode  (237),  the  second  leaf 
is  separated  from  the  preceding  by  half  the 
circumference  of  the  stem  ;  and,  having  completed  one  turn  round 
the  stem,  the  third  begins  a  second  turn.     In  the  tristichous,  each 


FIG.  170,  Piece  of  a  stalk,  with  the  sheathing  bases  of  the  leaves,  of  a  Sedge-Graas  (Carex 
Crus-corvi),  showing  the  three-ranked  arrangement.  171,  Diagram  of  the  cross-section  of  the 
Bame,  showing  two  cycles  of  leaves. 


THEIR   ARRANGEMENT. 


143 


leaf  is  separated  from  the  preceding  and  succeeding  by  one  third 
of  the  circumference,  there  are  three  leaves  in  one  turn,  or  cycle^ 
and  the  fourth  commences  a  second  cycle,  which  goes  on  in  the 
same  way.  That  is,  the  angular  divergence^  or  size  of  the  arc  in- 
terposed between  the  insertion  of  two  successive  leaves,  in  the  first 
is  ^,  in  the  second  ^,  of  the  circle.  These  fractions  severally  rep- 
resent, not  only  the  angle  of  divergence,  but  the  whole  plan  in 
these  two  modes  ;  the  numerator  denoting  the  number  of  times  the 
spiral  line  winds  round  the  stem  before  it  brings  a  leaf  directly 
over  the  one  it  began  with ;  while  the  denominator  expresses  ihe 
number  of  leaves  that  are  laid  down  in  this  course,  or  which  form 
each  cycle.  The  two-ranked  mode  (^)  is  evidently  the  simplest 
possible  case.  The  three-ranked  (^)  is  the  next,  and  the  one  in 
which  the  spiral  character  of  the  arrangement  172 

begins  to  be  evident.     It  is  further  illustrated  in 
the  next,  namely, 

239.  The  pentastichouSy  quincuncial^  or  five- 
ranked  arrangement  (Fig.  172).  This  is  much 
the  most  common  case  in  alternate-leaved  Dico- 
tyledonous plants.  The  Apple,  Cherry,  and  Pop- 
lar afford  ready  examples  of  it.  Here  there 
are  five  leaves  in  each  cycle,  since  we  must 
pass  on  to  the  sixth  before  we  find  one  placed 
vertically  over  the  first.  To  reach  this,  the  as- 
cending spiral  line  has  made  two  revolutions 
round  the  stem,  and  on  it  the  five  leaves  are 
equably  distributed,  at  intervals  of  f  of  the  cir- 
cumference. The  fraction  f  accordingly  ex- 
presses the  angular  divergence  of  the  successive 
leaves ;  the  numerator  indicates  the  number  of 
turns  made  in  completing  the  cycle,  and  the  de- 
nominator gives  the  number  of  leaves  in  the 
cycle,  or  the  number  of  vertical  ranks  of  leaves 
on  such  a  stem.     If  we  shorten  the  axis,  as  it  was  in  the  bud,  or 


.>= 


H 


FIG.  172.  Diagram  of  the  five-ranked  arrangement  of  the  leaves,  as  in  the  Apple-tree ;  a  spi- 
ral line  is  drawn  ascending  the  stem  and  passing  through  the  successive  scars  which  mark 
the  position  of  the  leaves  from  1  to  6.  It  is  made  a  dotted  line  where  it  passes  on  the  opposite 
side  of  the  stem,  and  the  scars  2  and  5,  which  come  on  that  side,  are  made  fainter.  173.  A 
plane,  horizontal  projection  of  the  same;  the  dotted  line  passing  from  the  edge  of  the  first  leaf 
to  the  second,  and  so  on  to  the  fifth  leaf,  which  completes  the  cycle ;  as  the  sixth  would  come 
over,  or  within  the  first. 


144  '  THE    LEAVES. 

make  a  horizontal  plan,  we  have  the  parts  disposed  as  in  the  dia- 
gram, Fig.  173,  the  lower  leaves  being  of  course  the  exterior. 

240.  The  eight-ranked  arrangement,  the  next  in  order,  is  like- 
wise not  uncommon.  It  is  found  in  the  Holly,  the  Callistemon  of 
our  conservatories,  the  Aconite,  the  tuft  of  leaves  at  the  base  of  the 
common  Plantain,  &c.  In  this  case  the  ninth  leaf  is  placed  over 
the  first,  the  tenth  over  the  second,  and  so  on ;  and  the  spiral  line 
makes  three  turns  in  laying  down  the  cycle  of  eight  leaves,  each 
separated  from  the  preceding  by  an  arc,  or  angular  divergence  of 
f  of  the  circumference. 

241.  All  these  modes,  or  nearly  all  of  them,  were  pointed  out 
by  Bonnet  as  long  ago  as  the  middle  of  the  last  century ;  but  they 
have  recently  been  extended  and  generalized,  and  the  mutual  re- 
lations of  the  various  methods  brought  to  light,  by  sagacious  recent 
researches,  principally  those  of  Schimper  and  Braun.  If  we  write 
down  in  order  the  series  of  fractions  which  represent  the  simpler 
forms  of  phyllotaxis  already  noticed,  as  determined  by  observation, 
viz.  ^,  •^,  f ,  f ,  we  can  hardly  fail  to  perceive  the  relation  that  they 
bear  to  each  other.  For  the  numerator  of  each  is  composed  of  the 
sum  of  the  numerators  of  the  two  preceding  fractions,  and  the  de- 
nominator of  the  sum  of  the  two  preceding  denominators.  (Also 
the  numerator  of  each  fraction  is  the  denominator  of  the  next  but 
one  preceding.)  We  may  carry  out  the  series  by  applying  this 
simple  law,  when  we  obtain  the  further  terms,  y^^j-,  -^j,  ^f ,  f  |,  &c. 
Now  these  numbers  are  those  which  are  actually  verified  by  obser- 
vation, and,  with  some  abnormal  exceptions,  this  series  comprises 
all  the  cases  that  occur.  These  higher  forms  are  the  most  common 
where  the  leaves  are  crowded  on  the  stem,  as  in  the  rosettes  of  the 

Houseleek  (Fig.  174),  and  the  scales  of  Pine- 
cones  (for  the  arrangement  extends  to  all  parts 
that  are  modifications  of  leaves),  or  where  they 
are  numerous  and  small  in  proportion  to  the  cir- 
cumference of  the  stem,  as  the  leaves  of  Firs, 
&c.  In  fact,  when  the  internodes  are  long  and 
the  base  of  the  leaves  large  in  proportion  to  the 
size  of  the  stem,  it  is  difficult,  and  often  impossi- 
ble to  tell  whether  the  8th,  13th,  or  21st  leaf 
stands  exactly  over  the  first.     When,  on  the  other  hand,  the  inter- 

FIG.  174.  An  offset  of  the  Houseleek,  with  the  rosette  of  leaves  unexpanded,  exhibiting  the 
5-13  arrangement;  the  fourteenth  leaf  being  directly  over  the  first. 


THEIR   ARRANGEMENT. 


145 


nodes  are  very  short,  so  that  the  leaves  touch  one  another,  or 
"nearly  so,  we  may  readily  perceive  what  leaves  are  superposed ; 
but  it  is  then  difficult  to  follow  the  succession  of  the  intermediate 
leaves.  When  this  cannot  be  directly  done,  however,  the  order 
may  be  deduced  by  simple  processes. 

242.  Sometimes  we  can  readily  count  the  number  of  vertical 
ranks,  which  gives  the  denominator  of  the  fraction  sought.  Thus, 
if  there  are  eight,  we  refer  the  case  to  the  f  arrangement  in  the 
regular  series ;  if  there  are  thirteen,  to  the  -^^  arrangement,  and 
so  on. 

243.  Commonly,  however,  when  the  leaves  are  crowded,  the 
vertical  ranks  are  by  no  means  so  manifest  as  two  or  more  orders 
of  oblique  series,  or  secondary  spirals,  which  are  at  once  seen  to 
wind  round  the  axis  in  opposite  directions,  as  in  the  Houseleek 
(Fig.  174  ;  where  the  numbers  1,6,  11  belong  to  a  spire  that  winds 
to  the  left,  1,9,  17  to  another  which  winds  to  the  right,  and  3,  6, 
9,  12  to  still  another  that  winds  in  the  same  direction)  :  they  are 
still  more  obvious  in  Pine-cones  (Fig.  175,  176).  These  oblique 
spiral  ranks  are  a  necessary  consequence  of  the  regular  ascending 
arrangement  of  parts  with  equal  intervals  over  the  circumference 
of  the  axis  :  and  if  the  leaves  are  numbered  consecutively,  these 
numbers  will  necessarily  stand  in  arithmetical  progression  on  the 
oblique  ranks,  and  have  certain  obvious  relations  with  the  primary 
spiral  which  originates  them  ;  as  will  be  seen  by  projecting  them 
on  a  vertical  plane. 

244.  Take,  for  example,  the  quincuncial 
where,  as  in  the  annexed  diagram,  the  ascend- 
ing spiral,  as  written  on  a  plane  surface,  ap- 
pears in  the  numbers  1,  2,  3,  4,  5,  6,  and  so 
on :  the  vertical  ranks  thus  formed,  beginning 
with  the  lowest  (which  we  place  in  the  middle 
column  that  it  may  correspond  with  the  Larch- 
cone,  Fig.  175,  where  the  lowest  scale,  1,  is 
turned  directly  towards  the  observer),  are  necessarily  the  numbers 
1,  6,  11  ;  4,  9,  14 ;  2,  7,  12  ;  5,  10,  15 ;  and  3,  8,  13.  But  two 
parallel  oblique  ranks  are  equally  apparent,  ascending  to  the  left ; 
viz.  1,  3,  5,  which,  if  we  coil  the  diagram  round  a  cylinder 
will  be  continued  into  7,  9,  11,  13,  15;    and  also  2,  4,  6,  8,  10, 

FIG.  175.  A  cone  of  the  small- fruited  American  Larch  (Larix  microcarpa),  with  the  scales 
numbered,  exhibiting  the  five-ranked  arrangement,  as  in  the  annexed  diagram. 

13 


(I) 

15 


arrangement, 


146  THE    LEAVES. 

which  runs  into  12,  14,  and  so  on,  if  the  axis  "be  further  prolonged. 
Here  the  circumference  is  occupied  by  two  secondary  left-hand 
series,  and  we  notice  that  the  common  difference  in  the  sequence 
of  numbers  is  two :  that  is,  the  number  of  the  parallel  secondary 
spirals  is  the  same  as  the  common  difference  of  the  numbers  on 
the  leaves  that  compose  them.  Again,  there  are  other  parallel  sec- 
ondary spiral  ranks,  three  in  number,  which  ascend  to  the  right ; 
viz,  1,  4,  7,  continued  into  10,  13 ;  3,  6,  9,  12,  continued  into 
15;  and  5,  8,  11,  14,  &c. ;  where  again  the  common  difference, 
3,  accords  with  the  number  of  such  ranks.  This  fixed  relation 
enables  us  to  lay  down  the  proper  numbers  on  the  leaves,  when 
too  crowded  for  directly  following  their  succession,  and  thus  to 
ascertain  the  order  of  the  primary  spiral  series  by  noticing  what 
numbers  come  to  be  superposed  in  the  vertical  ranks.  We  take, 
for  example,  the  very  simple  cone  of  the  small-fruited  American 
Larch  (Fig.  175),  which  usually  completes  only  two  cycles,  for 
we  see  that  the  lowest,  one  intermediate,  and  the  highest  scale,  on 
the  side  towards  the  observer,  stand  in  a  vertical  row.  Marking 
this  lowest  1,  and  counting  the  parallel  secondary  spirals  that  wind 
to  the  left,  we  find  that  two  occupy  the  whole  circumference. 
From  1,  we  number  on  the  scales  of  that  spiral  3,  5,  7,  and  so  on, 
adding  the  common  difference,  2,  at  each  step.  Again,  counting 
from  the  base  the  right-hand  secondary  spirals,  we  find  three  of 
these,  and  therefore  proceed  to  number  the  lowest  one  by  adding 
this  common  difference,  viz.  1,  4,  7,  10;  then,  passing  to  the  one 
next  to  it,  on  which  the  number  3  has  already  been  fixed,  we  carry 
on  that  sequence,  6,  9,  &c.  ;  and  on  the  third,  where  No.  5  is  al- 
ready fixed,  we  continue  the  numbering,  8,  11,  &c.  This  gives  us, 
in  the  vertical  rank  to  which  No.  1  belongs,  the  sequence  1,  6,  11, 
showing  that  the  arrangement  is  of  the  quincuncial  (f )  order.  It 
is  further  noticeable  that  the  smaller  number  of  parallel  secondary 
spirals,  2,  agrees  with  the  numerator  of  the  fraction  in  this  the  f 
arrangement ;  and  that  this  number  added  to  that  of  the  parallel 
secondary  spirals  which  wind  in  the  opposite  direction,  viz.  3, 
gives  the  denominator  of  the  fraction.  This  holds  good  through- 
out, so  that  we  have  only  to  count  the  number  of  parallel  second- 
ary spirals  in  the  two  directions,  and  assume  the  smaller  number 
as  the  numerator,  and  the  sum  of  this  and  the  larger  number  as  the 
denominator,  of  the  fraction  which  expresses  the  angular  diver- 
gence sought.     For  this  we  must  take,  however,  the  order  of  sec- 


THEIR   ARRANGEMENT. 


147 


ondary  spirals  nearest  the  vertical  rank  in  each  direction,  when 
there  are  more  than  two,  as  there  are  in  all  the  succeeding  cases. 
245.  A  similar  diagram  of  the  f  arrangement  introduces  a  third 
set  of  secondary  spirals,  in  addition  to  the  two  foregoing,  ascending 
in  a  nearer  approach  to  a  vertical  line,  and  with  a  higher  common 
difference,  viz.  5.  There  are  accordingly  five  of  this  sort,  viz. 
those  indicated  in  the  diagram  by  the  series  1,  6,  11,  16;  4,  9, 
14,  19,  24  ;  2,  7,  12,  17,  22  ;  5,  10,  15,  20,  25 ;  and  3,  8,  13,  18, 
23.     The  highest  obvious,  spiral  in  the  opposite  direction,  viz.  that 


Vertical  Projection 
of  the  I  Arrange- 
ment. 

25 
24 

23 
22 

21 
20 
19 

18 
17 
16 

15 
14 

13 
12 

n 

10 
9 
8 


Vertical  Projection  of  the  ^^ 
Arransement. 


27 


26 


25 


24 


23 


22 


21 


20 


19 


18 


17 


16 


15 


14 


13 


12 


11 


10 


of  which  the  series  1,  4,  7,  10,  13  is  a  specimen,  has  the  common 

FIG.  176.  A  cone  of  the  White  Pine,  on  which  the  numbers  are  laid  down,  and  the  leading 
higher  secondary  spirals  are  indicated :  those  with  the  common  difference  8  are  marked  by  dotted 
lines  ascending  to  the  right ;  two  of  the  five  that  wind  in  the  opposite  direction  are  also  marked 
with  dotted  lines :  the  set  with  the  common  difference  3,  in  one  direction,  and  that  with  the 
common  difference  2,  in  the  other,  are  very  manifest  on  the  cone. 


148  THE    LEAVES. 

difFerence  3,  and  gives  the  numerator,  and  S-\-5  the  denomina- 
tor, of  the  fraction  f .  The  next  case,  -y^^,  which  is  exempHfied  in 
the  rosettes  of  the  Houseleek  (Fig.  174)  and  in  the  cone  of  the 
White  Pine  (Fig.  176),  introduces  a  fourth  set  of  secondary  spi- 
rals, eight  in  number,  with  the  common  difference  8,  viz.  that  of 
which  the  series  1,  9,  17,  25  is  a  representative.  The  set  that 
answers  to  this  in  the  opposite  direction,  viz.  1,  6,  11,  16,  21,  26, 
with  the  common  difference  5,  gives  the  numerator,  and  5  -|-  8  the 
denominator,  of  the  fraction  y^^-.  We  may  here  compare  the  dia- 
gram with  an  actual  example  (Fig.  176) :  a  part  of  the  numbers 
are  of  course  out  of  sight  on  the  other  side  of  the  cone.  The 
same  laws  equally  apply  to  the  still  higher  modes. 

246.  The  order  is  uniform  in  the  same  species,  but  often  vari- 
ous in  allied  species.  Thus,  it  is  only  f  in  our  common  American 
Larch  ;  in  the  European  species,  ^\-.  The  White  Pine  is  -^\,  as  is 
also  the  White  Spruce  ;  but  other  Pines  with  thicker  cones  exhibit 
in  diflferent  species  the  fractions  ^\,  ^f ,  and  |-|^.  Sometimes  the 
primitive  spiral  ascends  from  left  to  right,  sometimes  from  right 
to  left.  One  direction  or  the  other  generally  prevails  in  each  spe- 
cies, yet  both  directions  are  not  unfrequently  met  with  even  in  the 
same  individual  plant. 

247.  But  when  a  branch  springs  from  a  stem  or  parent  axis, 
the  spiral  is  found  to  be  continued  directly  from  the  leaves  of 
the  stem  to  those  of  the  branch,  so  that  the  leaf  from  whose  axil 
the  branch  arises  begins  the  spire  of  that  branch.  When  the  spire 
of  the  branch  turns  in  the  same  direction  as  that  of  the  parent 
axis,  as  it  more  commonly  does,  it  is  said  to  be  homodromous 
(from  two  Greek  words,  signifying  like  course)  :  when  it  turns  in 
the  opposite  direction,  it  is  said  to  be  heterodromous  (or  of  unlike 
course ) . 

248.  The  cases  represented  by  the  fractions  J-,  -J,  and  f  are  the 
most  stable  and  certain,  as  well  as  the  easiest  to  observe.  In  the 
higher  forms,  the  exact  order  of  superposition  often  becomes  un- 
certain, owing  to  a  slight  torsion  of  the  axis,  or  to  the  difficulty 
of  observing  whether  the  9th,  14th,  21st,  35th,  or  56th  leaf  is  di- 
rectly over  the  first,  or  a  little  to  the  one  side  or  the  other  of  the 
vertical  line.  Indeed,  if  we  express  the  angle  of  divergence  in 
degrees  and  minutes,  we  perceive  that  the  difFerence  is  so  small  a 
part  of  the  circumference,  that  a  very  slight  change  will  substitute 
one  order  for  another.     The  divergence  in  -j^^  =:  138°  24'.     In  all 


THEIR    ARRANGEMENT.  149 

those  beyond,  it  is  137°  plus  a  variable  number  of  minutes,  which 
approaches  nearer  and  nearer  to  30'.  Hence  M.  Bravais  considers 
all  these  as  mere  alterations  of  one  typical  arrangement,  namely, 
with  the  angle  of  divergence  137°  30'  28",  which  is  irrational  to 
the  circumference,  that  is,  not  capable  of  dividing  it  an  exact  num- 
ber of  times,  and  consequently  never  bringing  any  leaf  precisely  in 
a  right  line  over  any  preceding  leaf,  but  placing  the  leaves  of  what 
we  take  for  vertical  ranks  alternately  on  both  sides  of  this  line  and 
very  near  it,  approaching  it  more  and  more,  without  ever  exactly 
reaching  it.  These  forms  of  arrangement  he  therefore  distin- 
guishes as  curviserial,  because  the  leaves  are  thus  disposed  on  an 
infinite  curve,  and  are  never  brought  into  exactly  straight  ranks. 
The  others  are  correspondingly  termed  rectiserial,  because,  as  the 
divergence  is  an  integral  part  of  the  circumference,  the  leaves  are 
necessarily  brought  into  rectilineal  ranks  for  the  whole  length  of 
the  stem.  Organic  forms  and  arrangements,  it  may  be  observed, 
always  have  a  degree  of  plasticity  and  power  of  adaptation,  even 
in  their  numerical  relations,  which  approximate,  but  are  never  en- 
tirely restricted  to  mathematical  exactness. 

249.  A  different  series  of  spirals  sometimes  occurs  in  alternate 
leaves,  viz.  ^,  -i,  f ,  y\  ;  and  still  others  have  been  met  with ; 
but  these  are  all  rare  or  exceptional  cases,  and  do^  not  require  to 
be  noticed  here. 

250.  Opposite  Leayes  (236).  The  arrangement  of  opposite  leaves 
usually  follows  very  simple  laws.  Almost  without  exception,  the 
second  pair  is  placed  over  the  intervals  of  the  first,  the  third  over 
the  intervals  of  the  second,  and  so  on.  More  commonly,  as  in 
plants  of  the  Labiate  or  Mint  Family,  the  successive  pairs  cross 
each  other  exactly  at  right  angles,  so  that  the  third  pair  stands  di- 
rectly over  the  first,  the  fourth  over  the  second,  &c.,  forming  four 
equidistant  vertical  ranks  for  the  whole  length  of  the  stem.  In 
this  case  the  leaves  are  said  to  be  decussate.  In  other  cases,  as  in 
the  Pink  Family,  it  may  often  be  observed  that  the  successive 
pairs  deviate  a  little  from  this  line,  so  that  we  have  to  pass  several 
pairs  before  we  find  one  exactly  superposed  over  the  pair  we  start 
with.  This  indicates  a  spiral  arrangement,  which  falls  into  some 
one  of  the  modes  already  illustrated  in  alternate  leaves,  only  that 
here  each  node  bears  a  pair  of  leaves. 

251.  Verticillate  or  Wliorled  Leaves  (236)  follow  the  same  modes  of 
arrangement  as  opposite  leaves.     Sometimes  they  decussate,  or  the 

13* 


150  THE    LEAVES. 

leaves  of  one  whorl  correspond  to  the  intervals  of  that  underneath, 
making  twice  as  many  vertical  ranks  as  there  are  leaves  in  the 
whorl ;  sometimes  they  wind  spirally,  so  that  each  leaf  of  the 
whorl  belongs  to  as  many  parallel  spirals,  analogous  to  the  second- 
ary spirals  in  the  case  of  alternate  leaves. 

252.  The  opposition  or*  alternation  of  the  leaves  is  generally 
constant  in  the  same  species,  and  often  through  the  same  family ; 
yet  the  transition  from  opposite  to  alternate  leaves  upon  the  same 
stem  is  not  very  rare  :  it  is  seen  in  the  common  Myrtle,  and  the 
Snapdragon.  All  Exogens,  having  their  cotyledons  or  embryo 
leaves  opposite,  necessarily  commence  with  that  mode  ;  many  re- 
tain it  throughout;  others  change  to  alternation,  either  directly  in 
the  primordial  leaves,  or  at  a  later  period  (231).  In  Endogens, 
on  the  contrary,  the  first  leaves  are  necessarily  alternate  (188), 
and  it  is  very  seldom  that  they  afterwards  exhibit  opposite  or 
whorled  leaves. 

253.  Only  one  leaf  arises  from  the  same  organic  point.  What 
are  called  fascicled  or  tufted  leaves  are  merely  those  of  an  axillary 
branch,  which  is  so  short  that  the  bases  of  the  leaves  are  in  con- 
tact.    This  is  plainly  seen  in  the  Barberry,  where,  the  primary 

leaves  hardening  into  a  kind  of 
thorn,  the  bud  in  its  axil  developes 
into  a  branch,  with  very  slight  elon- 
gation of  the  internodes.  Of  the 
same  nature  are  the  fascicled  leaves 
of  the  Pine,  and,  more  evidently, 
of  the  Larch  (Fig.  177),  where  the 
whole  foliage  of  such  branches  is 
developed  without  any  elongation  of  the  axis.  Some  of  these 
elongate  and  grow  on  through  the  summer,  producing  the  growth 
of  the  season,  on  which  the  leaves  are  distributed  so  as  to  show 
their  natural,  alternate  arrangement. 

254.  As  regards  their  position  on  the  stem,  leaves  are  said  to  be 
radical,  when  they  are  inserted  (235)  into  the  stem  at  or  below  the 
surface  of  the  ground,  so  as  apparently  to  grow  from  the  root,  as 
those  of  the  Plantain,  Primrose,  and  of  the  acaulescent  (139)  Vio- 
lets :  those  that  arise  along  the  main  stem  are  termed  cauline ; 
those  of  the  branches,  rameal ;  and  those  which  stand  upon  or  at 

FIG.  177.    Clustered  or  fascicled  leaves  of  the  Larch. 


VERNATION.  151 

the  base  of  flower-branches  are  called  Jloral ;  the  latter,  however, 
are  generally  termed  brads. 

255.  With  respect  to  succession,  those  leaves  which  manifestly 
exist  in  the  embryo  are  called  seminal ;  the  first  or  original  pair 
receiving  the  name  of  Cotyledons  (113),  and  usually  differing  wide- 
ly in  appearance  from  the  ordinary  leaves  which  succeed  them. 
The  earliest  ordinary  leaves,  termed  primordial,  as  well  as  the 
cotyledons,  usually  perish  soon  after  others  are  developed  to  sup- 
ply their  place. 

256.  As  pertaining  to  the  arrangement  of  leaves,  we  should  here 
notice  the  modes  in  which  they  are  disposed  before  expansion  in 
the  bud  ;  namely,  their 

257.  Vernation  or  Prscfoliation.  The  latter  is  the  most  character- 
istic name,  but  the  former,  given  by  Linnseus  (literally  denoting 
their  spring  state),  is  the  more  ancient  and  usual.  Two  things  are 
included  under  this  head  :  —  1st,  the  mode  in  which  each  leaf  con- 
sidered separately  is  disposed  ;  2d,  the  arrangement  of  the  several 
leaves  of  the  same  bud  in  respect  to  each  other.  This  last  is  evi- 
dently connected  with  phyllotaxis,  or  their  position  and  order  of 
succession  on  the  stem.  As  to  the  first,  leaves  are  for  the  most 
part  either  bent  or  folded,  or  rolled  up  in  vernation.  Thus,  the 
upper  half  may  be  bent  on  the  lower,  so  that  the  apex  of  the  leaf 
is  brought  down  towards  the  base,  as  in  the  Tulip-tree,  when  the 
leaves  are  injlexed  or  reclinate  in  vernation ;  or  the  leaf  may  be 
folded  along  its  midrib  or  axis,  so  that  the  right  half  and  the  left 
half  are  applied  together,  as  in  the  Oak  and  the  Magnolia,  when 
the  leaves  are  conduplicate  ;  or  each  leaf  may  be  folded  up  a  cer- 
tain number  of  times  like  a  fan,  as  in  the  Maple,  Currant,  and  Vine, 
when  they  are  said  to  be  plicate  or  plaited.  The  leaf  may  be 
rolled  either  parallel  with  its  axis,  or  on  its  axis.  In  the  latter  case 
it  is  spirally  rolled  up  from  the  apex  towards  the  base,  like  a  cro- 
sier, or  circinnate,  as  in  true  Ferns  (see  the  young  leaves  in  Fig. 
94),  and  among  Phsenogamous  plants  in  the  Drosera  or  Sundew. 
Of  the  former  there  are  three  ways ;  viz.  the  whole  leaf  may  be 
laterally  rolled  up  from  one  edge  into  a  coil,  with  the  other  edge 
exterior,  when  the  leaves  are  said  to  be  convolute,  as  in  the  Apri- 
cot and  Cherry ;  or  both  edges  may  be  equally  rolled  towards  the 
midrib  ;  either  inwards,  when  they  are  involute,  as  in  the  Violet  and 
the  Water  Lily  ;  or  else  outwards,  when  they  are  revolute,  as  in 
the  Rosemary  and  Azalea. 


152  THE    LEAVES. 

258.  Considered  relatively  to  each  other,  leaves  are  vdlvate  in 
vernation  when  corresponding  ones  touch  each  other  by  their 
edges  only,  without  overlapping :  they  are  imbricated  when  the 
outer  successively  overlap  the  inner,  by  their  edges  at  least,  in 
which  case  the  order  of  overlapping  exhibits  the  phyllotaxis,  or  or- 
der of  succession  and  position.  In  these  cases  the  leaves  are  plane 
or  convex,  at  least  not  much  bent  or  rolled.  When  leaves  with 
their  margins  involute  are  applied  together  in  a  circle  without  over- 
lapping, the  vernation  is  induplicate.  When  in  conduplicate  leaves 
the  outer  successively  embrace  or  sit  astride  of  those  next  within, 
the  vernation  is  equitanf,  as  the  leaves  of  the  Iris  at  their  base  :  or, 
when  each  receives  in  its  fold  the  half  of  a  corresponding  leaf 
folded  in  the  same  manner,  the  vernation  is  half-equitant  or  oh- 
volute.  These  terms  equally  apply  to  leaves  in  their  full-grown 
condition,  whenever  they  are  then  folded  or  placed  so  as  to  overlie 
or  embrace  one  another.  They  likewise  apply  to  the  parts  in  the 
flower-bud,  under  the  name  of  aestivation  or  prsefloration. 

Sect.  II.    Their  Structure  and  Conformation. 

259.  Anatomy  of  the  Leaf.  The  complete  leaf  consists  of  the 
Blade  (Lamina  or  Limb),  with  its  Petiole  or  Leafstalk,  and 
at  its  base  a  pair  of  Stipules.  Of  these  the  latter  are  frequently 
absent  altogether,  or  else  they  fall  away  as  the  leaf  expands :  the 
petiole  is  very  often  wanting,  when  the  leaf  is  sessile,  or  has  its 
blade  resting  immediately  on  the  stem  that  bears  it.  Sometimes, 
moreover,  there  is  no  proper  blade  or  expanded  portion,  but  the 
whole  organ  is  cylindrical  or  stalk-like.  It  is  the  general  charac- 
teristic of  the  leaf,  however,  that  it  is  an  expanded  body.  Indeed, 
it  may  be  viewed  as  a  contrivance  for  increasing  the  green  surface 
of  a  plant,  so  as  to  expose  to  the  light  and  air  the  greatest  practi- 
cable amount  of  parenchyma  containing  the  green  matter  of  vege- 
tation (chlorophyll,  87),  upon  which  the  light  exerts  its  peculiar  ac- 
tion. In  a  general,  mechanical  way,  it  may  be  said  leaves  are  defi- 
nite protrusions  of  the  green  layer  of  the  bark,  expanded  horizon- 
tally into  a  thin  lamina,  and  stiffened  by  tough,  woody  fibres  (con- 
nected both  with  the  liber,  or  inner  bark,  and  the  wood),  which  form 
its  framework,  ribs,  or  veins.  Like  the  stem,  therefore,  the  leaf 
is  made  up  of  two  distinct  parts,  the  cellular  and  the  icoody.  The 
cellular  portion  is  the  green  pulp  or  parenchyma :  the  woody,  is 


THEIR   ANATOMY.  153 

the  skeleton  or  framework  which  ramifies  among  and  strengthens 
the  former. 

260.  The  woody  or  fibrous  portion  fulfils  the  same  purposes  in 
the  leaf  as  in  the  stem,  not  only  giving  firmness  and  support  to  the 
delicate  cellular  apparatus,  but  also  serving  for  the  conveyance  and 
distribution  of  the  sap.  The  subdivision  of  these  ribs,  or  veins,  of 
the  leaf,  as  they  are  not  inappropriately  called,  continues  beyond 
the  limits  of  unassisted  vision,  until  the  bundles  or  threads  of  woody 
tissue  are  reduced  to  nearly  separate  fibres,  ramified  throughout  the 
green  pulp,  so  as  to  convey  to  every  portion  the  sap  it  consumes. 

261.  The  cellular  portion,  or  parenchyma,  of  the  leaf  is  not  a 
structureless,  pulpy  mass,  such  as  it  appears  to  the  naked  eye. 
The  cliloropliyll  (87),  to  which  the  green  color  is  entirely  owing, 
and  which  consists  of  innumerable  rounded  globules,  is  all  inclosed 
in  cells  of  lax  parenchyma  (51)  ;  and  these  cells  are  not  heaped 
promiscuously,  but  exhibit  a  regular  arrangement ;  upon  a  plan, 
too,  which  varies  in  different  parts  of  the  leaf,  according  to  the  dif- 
ferent conditions  in  which  it  is  placed. 

262.  Leaves  are  almost  always  expanded  horizontally,  so  as  to 
present  one  surface  to  the  ground  and  the  other  to  the  sky ;  and 
the  parenchyma  forms  two  general  strata,  one  belonging  to  the  up- 
per and  the  other  to  the  lower  side.  The  microscope  displays  a 
manifest  difierence  in  the  parenchyma  of  these  two  strata.  That 
of  the  upper  stratum  is  composed  of  one,  two,  three,  or  several 
compact  layers  of  oblong  cells, 
placed  endwise,  or  with  their 
long  diameter  perpendicular  to 
the  surface ;  while  that  of  the 
lower  is  very  loosely  arranged, 
leaving  numerous  vacant  spaces 
between  the  cells ;  and  when 
the  cells  are  oblong,  their  longer 
diameter  is  parallel  with  the  epi- 
dermis.    This  is  shown  in  Fig.  j^g 

7,  which  represents  a  magnified 

section  through  the  thickness  (perpendicular  to  the  surface)  of  a 

leaf  of  the  Star- Anise  of  Florida  ;  where  the  upper  stratum  of  pa- 

FIG.  173.  Magnified  section  through  the  thickness  of  a  leaf  of  the  Garden  Balsam  :  a,  sec- 
lion  of  the  epidermis  of  the  upper  surface  ;  b,  of  the  upper  stratum  of  parenchyma ;  c,  of  the 
lower  stratum;  d,  of  the  epidermis  of  the  lower  surface. 


154 


THE    LEAVES. 


renchyma  consists  of  only  a  single  series  of  perpendicular  cells. 
Also  in  Fig.  178  (after  Brongniart),  which  represents  a  similar  view 
of  a  thin  slice  of  a  leaf  of  the  Garden  Balsam.  Fig.  179  represents 
a  similar  section  through  the  thickness  of  a  leaf  of  the  White  Lily  ; 
where  the  upper  stratum  is  composed  of  only  one  compact  lay- 
er of  vertical  cells.  The  parenchyma  is  alone  represented  ;  the 
woody  portion,  or  veins,  being  left  out.  This  structure  shows  why 
the  upper  surface  of  leaves  is  of  a  deeper  green  than  the  lower. 

263.  The  object  which  this  arrangement  subserves  will  appear 
evident,  when  we  consider  that  the  spaces  between  the  cells,  filled 
with  air,  communicate  freely  with  each  other  throughout  the  leaf, 
and  also  with  the  external  air  (by  means  of  holes  in  the  epidermis 
presently  to  be  described) ;  and  when  we  consider  the  powerful 
action  of  the  sun  to  promote  evaporation,  especially  in  dry  air ;  and 
that  the  thin  walls  of  the  cells,  like  all  vegetable  membrane,  allow 


of  the  free  escape  of  the  contained  moisture  by  transudation.  The 
compactness  of  the  cells  of  that  stratum  which  is  presented  immedi- 
ately to  the  sun,  and  their  vertical  elongation,  so  that  each  shall 


FIG.  179.  Magnified  section  through  the  thickness  of  the  leaf  of  the  White  Lily,  showing 
the  parenchyma,  and  the  epidermis  of  both  surfaces ;  the  lower  pierced  with  stomata.  (After 
Brongniart.)  180.  Two  of  the  cells  of  the  upper  stratum  of  parenchyAia,  detached  and  more 
magnified,  showing  the  contained  grains  of  chlorophyll. 

FIG.  181.  Magnified  view  of  the  10,000th  part  ofa  square  inch  of  the  epidermis  of  the  lower 
surface  of  the  White  Lily,  with  the  stomata,  or  breathing  pores,  it  bears.  These  are  unusually 
large  in  the  Lily,     die  is  shown  more  magnified  in  Fig.  182:  and  widely  open  in  Fig.  183. 

FIG.  134.  Magnified  perpendicular  section  through  the  thickness  of  the  epidermis  ahd  upper 
stratum  of  parenchyma  in  the  leaf  of  the  Oleander  (after  Brongniart);  showing  the  epidermis 
of  three  layers  of  thick-sided  cells,  aird  the  upper  parenchyma  of  very  compact  vertical  cells. 


THEIR    ANATOMY.  155 

expose  the  least  possible  surface,  obviously  serve  to  protect  the 
loose  parenchyma  beneath  from  the  too  powerful  action  of  direct 
sunshine.  This  provision  is  the  more  complete  in  the  case  of 
plants  indigenous  to  arid  regions,  where  the  soil  is  usually  so 
parched  during  the  dry  season,  that,  for  a  long  period,  it  affords 
only  the  scantiest  supply  of  moisture  to  the  roots.  Compare,  in 
this  respect,  the  leaf  of  the  Lily  (Fig.  179),  where  the  upper  stra- 
tum contains  but  a  single  layer  of  barely  oblong  cells,  with  that  of 
the  Oleander  (which  is  obliged  to  stand  a  season  of  drought),  the 
upper  stratum  of  which  consists  of  two  layers  of  long  and  narrow 
vertical  cells  as  closely  compacted  as  possible  (Fig.  184).  So 
different  is  the  organization  of  the  two  strata,  that  a  leaf  soon  per- 
ishes if  reversed  so  as  to  expose  the  lower  surface  to  direct  sunshine. 

264.  A  further  and  more  effectual  provision  for  restraining  the 
perspiration  of  leaves  within  due  limits  is  found  in  the  epidermis, 
or  skin,  that  invests  the  leaf,  as  it  does  the  whole  surface  of  the  veg- 
etable, and  which  is  so  readily  detached  from  the  succulent  leaves 
of  such  plants  as  the  Stone-crop  and  the  Live-for-ever  (Sedum) 
of  the  gardens.  The  Epidermis  (69)  is  composed  of  small  cells 
belonging  to  the  outermost  layer  of  cellular  tissue,  with  the  pretty 
thick-sided  walls  very  strongly  coherent,  so  as  to  form  a  firm  mem- 
brane. Its  cells  usually  contain  no  chlorophyll.  In  ordinary 
herbs  that  allow  of  ready  evaporation,  this  membrane  is  made  up 
of  a  single  layer  of  cells ;  as  in  the  Lily,  Fig.  179,  and  the  Balsam, 
Fig.  178.  It  is  composed  of  two  layers  in  cases  where  one  might 
prove  insufficient ;  and  in  the  Oleander,  besides  the  provision  al- 
ready described,  the  epidermis  consists  of  three  layers  of  very 
thick-sided  cells  (Fig.  184).  It  is  generally  thick,  or  hard  and 
impermeable,  in  the  firm  leaves  of  the  Pittosporum,  Laurustinus,. 
&c.,  which  will  thrive,  for  this  very  reason,  where  other  plants  are 
liable  to  perish,  in  the  dry  atmosphere  of  our  rooms  in  winter. 

265.  In  such  firm  leaves,  especially,  the  walls  of  the  epidermal 
cells  are  soon  thickened  by  secondary  deposition  (39),  especially 
on  the  superficial  side.  This  is  well  seen  in  the  epidermis  of  the 
Aloe,  and  in  other  fleshy  plants,  which  bear  severe  drought  with 
impunity :  in  Fig.  185,  it  is  shown,  at  «,  in  the  rind  of  a  Cactus, 
where  the  green  layer  of  the  whole  stem  answers  the  purpose  of 
the  leaves.  Sometimes  an  exterior  layer  of  this  superficial  de- 
posit in  the  epidermis,  or  a  secretion  from  it,  may  be  detached 
in  the  form  of  a  continuous,  apparently  structureless  membrane. 


156 


THE    LEAVES. 


which  Brongniart  and  succeeding  authors  have  called  the  Cuticle. 
Tiiat  it  may  shed  water  readily,  the  surface  of  leaves  is  commonly 
protected  by  a  very  thin  varnish  of  wax,  or  else  with  a  hloom  of  the 
same  substance  in  the  form  of  a  whitish  powder,  which  easily  rubs 
oflf  (86),  as  familiarly  seen  in  a  cabbage-leaf. 


266.  A  thickening  deposit  sometimes  takes  place  in  the  cells  of 
parenchyma  immediately  underneath  the  epidermis,  especially  in 
the  Cactus  Family,  where  the  once  thin  and  delicate  walls  of  the 
cells  become  excessively  and  irregularly  thickened,  so  as  doubtless 
greatly  to  obstruct  or  arrest  all  exhalation  through  the  rind.  Some- 
thing like  this  choking  of  the  cells  must  commonly  occur  with  age 
in  most  leaves,  particularly  those  that  live  for  more  than  one  season. 

267.  But  the  multiplication  of  these  safeguards  against  exhala- 
tion might  be  liable  to  defeat  the  very  objects  for  which  leaves  are 
principally  destined.  Evaporation  from  the  parenchyma  of  the 
leaves  is  essential  to  the  plant,  as  it  is  the  only  method  by  which 
its  excessively  dilute  food  can  be  concentrated.  Some  arrange- 
ment is  requisite  that  shall  allow  of  sufficient  exhalation  from  the 
leaves  while  the  plant  is  freely  supplied  with  moisture  by  the  roots, 
but  restrain  it  when  the  supply  is  deficient.  It  is  clear  that  the 
greatest  demand  is  made  upon  the  leaves  at  the  very  period  when 
the  supply  through  the  roots  is  most  likely  to  fail :  for  the  sum- 
mer's sun,  which  acts  so  powerfully  on  the  leaves,  at  the  same 
time  parches  the  soil  upon  which  the  leaves  (through  the  rootlets) 
depend  for  the  moisture  they  exhale.  So  long  as  their  demands 
are   promptly  answered,  all  goes  well.     The  greater  the  force  of 


FIG.  18.5.  Magnified  slice  of  the  epidermis  and  superficial  parenchyma  of  a  Cactus,  after 
Schleiden;  exhibiting  the  epidermis  greatly  thickened  by  a  stratified  deposition  in  the  cells: 
and  the  cells  of  the  parenchyma  likewise  nearly  filled  with  an  incrusting  deposit.  The  depo- 
sition in  such  cases  is  always  irregular,  leaving  canals  or  passages  which  nearly  connect  the 
adjacent  cells.     Several  of  the  cells  contain  crystals  (91). 

FIG.  186.  Similar  section  from  another  species  of  Cactus,  passing  through  one  of  the  sto- 
mata,  and  the  deep  intercellular  space  beneath  it. 


THEIR   ANATOMY.  157 

the  sun's  rays,  the  greater  the  speed  at  which  the  vegetable  ma- 
chinery is  driven.  But  whenever  the  supply  at  the  root  fails,  the 
foliage  begins  to  flag  and  droop,  as  is  so  often  seen  under  a  sultry 
meridian  sun ;  and  if  the  exhaustion  proceeds  beyond  a  certain 
point,  the  leaves  inevitably  wither  and  perish.  Some  adaptation  is 
therefore  needed,  analogous  to  the  governor  in  machinery,  or  the 
self-acting  valve,  which  shall  regulate  the  exhalation  according  to 
the  supply.      Such  an  office  is  actually  fulfilled  by 

268.  The  Stomata,  Slomates^  or  Breathing-pores  (70).  Through 
the  valvular  orifices  which  bear  this  name,  exhalation  principally 
takes  place,  in  all  ordinary  cases,  where  the  epidermis  is  thick  and 
firm  enough  to  prevent  much  escape  of  moisture  by  direct  transu- 
dation. The  stomata  (Fig.  181-183,  187)  are  situated  so  as  to 
open  directly  into  the  hollow  chambers,  or  air-cavities,  which  per- 
vade the  parenchyma  (Fig.  179,  186),  especially  the  lower  stra- 
tum ;  so  as  to  afford  free  communication  between  the  external  air 
and  the  whole  interior  of  the  leaf.  The  perforation  of  the  epider- 
mis is  between  two  (or  rarely  four)  small  and  delicate  cells,  which, 
unlike  the  rest  of  the  epidermis,  usually  contain  some  chloro- 
phyll, and  in  other  respects  resemble  the  parenchyma  beneath. 
Their  exact  mechanism  is  not  very  well  made  out ;  but  it  appears 
that,  when  moist,  these  hygrometric  cells  become  turgid,  and  in 
elongating  diverge  or  curve  outwardly  in  their  middle,  where  they 
do  not  cohere,  so  as  to  open  a  free  communication  between  the 
outer  air  and  the  interior  of  the  leaf.  When  dry,  they  incline  to 
shorten  and  straighten,  so  as  to  bring  their  sides  into  contact  and 
close  the  orifice  completely.  This  structure  is  sufficiently  illus- 
trated in  the  figures  referred  to,  and  es- 
pecially in  those  of  the  Lily,  where  the 
stomata  are  unusually  large  and  easy  of 
examination.  The  action  and  use  of 
this  mechanism  will  readily  be  under- 
stood. So  long  as  the  leaf  is  in  a  moist 
atmosphere,  and  is  freely  supplied  with 
sap  by  the  stem  and  roots,  the  cells  that 
guard  the  orifice  are  expanded,  and  the 
open  stomata  allow  the  free  escape  of 
moisture  by  evaporation.     But  when  the  supply  fails,  and  the  pa- 

FIG.  187,    A  highly  magnified  piece  of  the  epidermis  of  the  Garden  Balaam,  with  three 
stomata  (after  Brongniart). 

14 


158  THE    LEAVES. 

renchyma  begins  to  be  exhausted,  the  guardian  cells,  at  least 
equally  affected  by  the  dryness,  quickly  collapse,  and  by  closing 
these  thousands  of  apertures  check  the  drain  the  moment  it  be- 
comes injurious  to  the  plant. 

269.  As  a  general  rule,  the  stomata  wholly  or  principally  belong 
to  the  epidermis  of  the  lower  surface  of  the  leaf:  the  mechanism 
is  too  delicate  to  work  well  in  direct  sunshine.  The  position  of 
the  stomata,  and  the  loose  texture  of  the  lower  parenchyma,  re- 
quire that  this  surface  should  be  shielded  from  the  sun's  too  direct 
and  intense  action  ;  and  show  why  leaves  soon  perish  when  artifi- 
cially reversed,  and  prevented  from  resuming  (as  otherwise  they 
spontaneously  will)  their  natural  position.  This  general  arrange- 
ment is  variously  modified,  however,  under  peculiar  circumstances. 
The  stomata  are  equally  distributed  on  the  two  sides  of  those 
leaves,  of  whatever  sort,  which  grow  in  an  erect  position,  or  pre- 
sent their  edges,  instead  of  their  surfaces,  to  the  earth  and  sky 
(294),  and  have  the  parenchyma  of  both  sides  similarly  constituted, 
sustaining  consequently  the  same  relations  to  light.  In  the  Water- 
Lilies  (Nymphsea,  Nuphar),  and  other  leaves  which  float  upon  the 
water,  the  stomates  all  belong  to  the  upper  surface  ;  and  all  leaves 
growing  under  water,  where  there  can  be  no  evaporation,  are  des- 
titute, not  only  of  stomates,  but  usually  of  a  distinct  epidermis  also. 

270.  The  number  of  the  stomata  varies  in  different  leaves  from 
800  to  about  170,000  on  the  square  inch  of  surface.  In  the  Apple, 
there  are  said  to  be  about  24,000  to  the  square  inch  (which  is  un- 
der the  average  number,  as  given  in  a  table  of  36  species  by  Lind- 
ley) ;  so  that  each  leaf  of  that  tree  would  present  about  100,000  of 
these  orifices.  From  their  great  numbers,  they  are  doubtless  fully 
adequate  to  the  office  that  is  attributed  to  them,  notwithstanding 
their  minute  size.  Their  size  varies  so  greatly  in  different  plants, 
that  no  safe  inference  can  be  drawn  of  the  comparative  amount  of 
exhalation  in  different  leaves  from  the  mere  number  of  their  sto- 
mata. When  the  stomata  are  not  all  restricted  to  the  lower  sur- 
face, still  the  greater  portion  usually  occupy  this  position.  Thus, 
the  leaf  of  Arum  Dracontium  is  said  to  have  8,000  stomata  to  a 
square  inch  of  the  upper  surface,  and  twice  that  number  in  the 
same  space  of  the  lower.  The  leaf  of  the  Coltsfoot  has  12,000 
stomata  to  a  square  inch  of  the  lower  epidermis,  and  only  1,200  in 
the  upper.  That  of  the  White  Lily  60,000  to  the  square  inch  on 
the  lower  surface,  and  perhaps  3,000  on  the  upper. 


THEIR   ANATOMY.  159 

271.  At  the  points  on  the  surface  of  the  developing  leaf  where 
stomates  are  about  to  be  formed,  one  of  the  epidermal  cells  early- 
ceases  to  enlarge  and  thicken  with  the  rest,  but  divides  into  two  (in 
the  manner  formerly  described,  32),  forming  the  two  guardian 
cells :  as  they  grow,  the  two  constituent  portions  of  their  common 
partition  separate,  leaving  an  interspace  or  orifice  between.  In 
some  cases,  each  new  cell  divides  again,  when  the  stomate  is 
formed  of  four  cells  in  place  of  two. 

272.  Succulent  or  fleshy  plants,  such  as  those  of  the  Cactus 
tribe,  Mesembryanthemums,  Sedums,  Aloes,  &c.,  are  remarkable 
for  holding  the  water  they  imbibe  with  great  tenacity,  rather  in 
consequence  of  the  thickness  of  the  epidermis,  or  from  the  deposit 
which  early  accumulates  in  the  superficial  cells  of  the  parenchyma 
(265),  than  from  the  want  of  stomata.  The  latter  are  usually 
abundant,*  but  they  seem  to  remain  closed,  or  to  open  less  than  in 
ordinary  plants,  except  in  young  and  growing  parts.  Hence  the 
tissue  becomes  gorged  as  it  were  with  fluid,  which  is  retained  with 
great  tenacity,  especially  during  the  hot  season.  They  are  evi- 
dently constructed  for  enduring  severe  droughts ;  and  are  accord- 
ingly found  to  inhabit  dry  and  sunburnt  places,  such  as  the  arid 
plains  of  Africa,  —  the  principal  home  of  the  Stapelias,  Aloes,  suc- 
culent Euphorbias,  &;c., —  or  the  hottest  and  driest  parts  of  our 
own  continent,  to  which  the  whole  Cactus  Family  is  indigenous. 
Or,  when  such  plants  inhabit  the  cooler  temperate  regions,  like 
the  Sedums  and  the  common  Houseleek,  &c.,  they  are  commonly 
found  in  the  most  arid  situations,  on  naked  rocks,  old  walls,  or 
sandy  plains,  exposed  to  the  fiercest  rays  of  the  noonday  sun,  and 
thriving  under  conditions  which  would  insure  the  speedy  destruc- 
tion of  ordinary  plants.  The  drier  the  atmosphere,  the  greater 
their  apparent  reluctance  to  part  with  the  fluid  they  have  accumu- 
lated, and  upon  which  they  live  during  the  long  period  when  little 
or  no  moisture  is  yielded  by  the  soil  or  the  air.  Their  structure 
and  economy  fully  explain  their  tolerance  of  the  very  dry  air  of 
our  houses  in  mid-winter,  when  ordinary  thin-leaved  plants  become 
unhealthy  or  perish. 

273.  Sometimes  the  leaves  of  succulent  plants  merely  become 

*  The  thickened  epidermis  of  the  fleshy  leaves  of  the  Sea-Sand  wort  (Hon- 
kenya)  is  provided  with  an  abundance  of  large  stomata,  on  the  upper  as  well 
as  the  lower  face.  But  this  plant,  though  very  Beshy,  grows  in  situations 
where  its  roots  are  always  supplied  with  moisture. 


160  THE    LEAVES. 

obese  or  misshapen,  like  those  of  the  Ice-plant  and  other  species 
of  Mesembryanthemum,  &c. :  sometimes  they  are  reduced  to  tri- 
angular projections  or  points,  or  are  perfectly  confounded  with  the 
unusually  developed  green  bark  of  the  stem,  which  fulfils  their 
office,  as  in  the  Stapelia  and  most  Cacti. 

274.  The  Development  of  Leaves  proceeds  from  the  apex  (which 
first  appears,  in  the  form  of  a  little  tumor  or  papilla)  towards  the 
base,  which  is  later  eliminated  from  the  axis.  The  apex  is  pushed 
forward  by  the  formation  and  growth  of  the  parts  beneath  :  after 
the  blade  has  shaped  itself,  the  rudiment  of  the  petiole,  if  there  is 
to  be  any,  begins  to  be  visible,  and  this  grows  in  like  manner  from 
the  apex  downwards,  the  lower  part  of  it  being  the  last  formed  : 
its  growth  subsequent  to  its  first  formation  is  greater  in  proportion 
to  its  original  size  than  that  of  any  other  part  of  the  leaf.  The 
sheath  at  the  base  (as  in  most  Monocotyledons),  or  the  stipules 
(304,  which  principally  belong  to  Dicotyledons),  are  at  first  con- 
tinuous with  the  blade,  or  divided  from  it  by  a  mere  constriction : 
the  formation  and  elongation  of  the  petiole  soon  separate  them. 
The  stipules,  remaining  next  the  axis  or  source  of  nourishment,  un- 
dergo a  rapid  development  early  in  the  bud,  so  that,  at  a  certain 
stage,  they  are  often  larger  than  the  body  of  the  leaf,  and  they  ac- 
cordingly form  in  such  cases  the  teguments  of  the  bud..  Divided 
or  lobed  and  compound  leaves  are  simple  at  the  commencement, 
but  the  lobes  are  very  early  developed  ;  they  grow  in  respect  to 
the  axis  of  the  leaf  nearly  as  that  grew  from  the  axis  of  the  plant, 
and  in  the  compound  leaf  at  length  isolate  themselves,  and  are 
often  raised  on  footstalks  of  their  own.  Commonly  the  upper 
lobes  or  leaflets  are  first  formed,  and  then  the  lower:  but  in  those 
of  the  Walnut  and  Ailanthus,  and  other  large  compound  leaves, 
new  leaflets  continue  to  be  produced  from  the  apex,  even  after  the 
lowermost  are  nearly  full  grown.  In  the  earliest  stage  leaves  con- 
sist of  parenchyma  alone  :  the  fibro-vascular  tissue  which  makes 
the  ribs,  veins,  or  framework  appears  later.  No  good  researches 
have  yet  been  made  upon  the  mode  and  order  of  its  production. 

275.  The  Forms  of  Leaves  are  almost  infinitely  various.  These 
aflTord  some  of  the  readiest,  if  not  the  most  certain,  marks  for  char- 
acterizing species.  Their  principal  modifications  are  therefore 
classified,  minutely  defined,  and  embodied  in  a  system  of  nomen- 
clature which  is  equally  applicable  to  other  parts  of  the  plant,  and 
which  as  an  instrument  is  indispensable  to  the  systematic  botanist. 


THEIR    FORMS   AND    VENATION.  161 

The  numerous  entirely  unconnected  technical  terms  which  have 
gradually  accumulated  from  the  infancy  of  the  science,  and  have 
multiplied  with  its  increasing  wants,  are  mostly  quite  arbitrary, 
or  have  been  suggested  by  real  or  fancied  resemblances  of  their 
shapes  to  natural  or  other  objects.  This  arbitrary  nomencla- 
ture, which  formerly  severely  tasked  the  memory  of  the  student, 
was  reduced  by  De  Candolle  to  a  clear  and  consistent  system, 
based  upon  scientific  principles,  and  of  easy  application.  The 
fundamental  idea  of  the  plan  is,  that  the  almost  infinite  varieties  in 
the  form  and  outline  of  leaves  may  be  deduced  from  the  different 
modes  and  degrees  in  which  the  woody  skeleton  or  framework  of 
the  leaf  is  expanded  or  ramified  in  the  parenchyma.  Upon  this 
conception  our  following  sketch  is  based ;  in  which  we  endeavour 
to  introduce  and  define  the  more  important  terms  of  the  nomencla- 
ture of  leaves.  It  should  be  kept  in  mind,  however,  that  this  sys- 
tem is  partly  if  not  altogether  empirical,  and  is  not  to  be  taken  as 
an  explanation  of  the  actual  formation  of  the  leaf;  but  rather  as 
an  account  of  the  mutual  adaptation  and  correspondence  of  the 
outlines  and  the  framework  of  leaves.  For  the  parenchyma  is  de- 
veloped, and  the  form  of  the  leaf  is  often  fixed,  before  the  frame- 
work has  an  existence.  The  latter,  therefore,  cannot  have  deter- 
mined tha  outline  or  shape  of  the  organ.  The  distribution  of  the 
veins  or  fibrous  framework  of  the  leaf  in  ihe  blade  is  termed  its 

276.  Yenation.  The  veins  are  distributed  throughout  the  lamina 
in  two  principal  modes.  Either  the  vessels  of  the  petiole  divide  at 
once,  where  they  enter  the  blade,  into  several  veins,  which  run 
parallel  with  each  other  to  the  apex,  connected  only  by  simple 
transverse  veinlets  (as  in  Fig.  201) ;  or  the  petiole  is  continued 
into  the  blade  in  the  form  of  one  or  more  principal  or  coarser 
veins,  which  send  off  branches  on  both  sides,  the  smaller  branch- 
lets  uniting  with  one  another  (anastomosing)  and  forming  a  kind 
of  network;  as  in  Fig.  191, 199.  The  former  are  termed  parallel' 
veined,  or  commonly  nerved  leaves ;  the  veins  in  this  case  having 
been  called  nerves  by  the  older  botanists,  —  a  name  which  it  is 
found  convenient  to  retain,  although  of  course  they  are  in  no  re- 
spect analogous  to  the  nerves  of  animals.  The  latter  are  termed 
reticulated  or  netted-veined  leaves. 

277.  Parallel-veined  or  nerved  leaves  are  characteristic  of  En- 
dogenous plants ;  while  reticulated  leaves  are  almost  universal  in 
Exogenous  plants.    We  are  thus  furnished  with  a  very  obvious,  al- 

14* 


162 


THE  LEAVES. 


though  by  no  means  absolute,  distinction  between  these  two  great 
classes  of  plants,  independently  of  the  structure  of  their  stems  (185). 
278.  In  reticulated  leaves,  the  coarse  primary  veins  (one  or 
more  in  number),  which  proceed  immediately  from  the  apex  of 
the  petiole,  are  called  rihs ;  the  branches  are  termed  veins,  and 
their  subordinate  ramifications,  veinlets.  Very  frequently,  a  single 
strong  rib  (called  the  midrib),  forming  a  continuation  of  the  peti- 
ole, runs  directly  through  the  middle  of  the  blade  to  the  apex  (Fig. 
196,  197,  &c.),  and  from  it  the  lateral  veins  all  diverge.  Such 
leaves  are  termed  feather-veined  or  pinnately  veined ;  and  are 
subject  to  various  modifications,  according  to  the  arrangement  of 
the  veins  and  veinlets ;  the  primary  veins  sometimes  passing 
straight  from  the  midrib  to  the  margin,  as  in  the  Beech  and  Chest- 
nut (Fig.  196) ;  while  in  other  cases  they  are  divided  into  veinlets 
long  before  they  reach  the  margin.  When  the  midrib  gives  oflT  a 
very  strong  primary  vein  or  branch  on  each  side  above  the  base, 
the  leaf  is  said  to  be  triple-ribbed,  or  often  tripli-nerved,  as  in  the 
common  Sunflower  (Fig.  199)  ;  if  two  such  ribs  proceed  from  each 
side  of  the  midrib,  it  is  said  to  be  quintuple-ribbed,  or  quintupli- 
nerved. 


197         198  199  200  201 

279.     Not  unfrequently  the  vessels  of  a  reticulated  leaf  divide  at 


FIG.  183-201.    Various  forms  of  simple  leaves. 


THEIR  FORMS  AND  VENATION.  163 

the  apex  of  the  petiole  into  three  or  more  portions  or  ribs  of  nearly- 
equal  size,  which  are  usually  divergent,  each  giving  off  veins  and 
veinlets,  like  the  single  rib  of  a  feather-veined  leaf.  Such  leaves 
are  termed  radiated-veined,  or  palmately  veined ;  and,  as  to  the 
number  of  the  ribs,  are  called  three-ribbed,  five-ribbed,  seven- 
ribbed,  &c.  (Fig.  191,  203,  209).  Examples  of  this  form  are  fur- 
nished by  the  Maple,  the  Gooseberry,  the  Mallow  Family,  &c. 
Occasionally  the  ribs  of  a  radiated-veined  leaf  converge  and  run  to 
the  apex  of  the  blade,  as  in  Rhexia  and  other  plants  of  the  same 
family,  thus  resembling  a  parallel-veined  or  nerved  leaf;  from 
which,  however,  it  is  distinguished  by  the  intermediate  netted 
veins.  But  when  the  ribs  are  not  very  strong,  such  leaves  are  fre- 
quently said  to  be  nerved,  although  they  branch  before  reaching 
the  apex. 

280.  According  to  the  theory  of  De  Candolle  (275),  the  shape 
which  leaves  assume  may  be  considered  to  depend  upon  the  dis- 
tribution of  the  veins,  and  the  quantity  of  parenchyma ;  the  gen- 
eral outline  being  determined  by  the  division  and  direction  of  the 
veins  ;  and  the  form  of  the  margin,  (whether  even  and  continuous, 
or  interrupted  by  void  spaces  or  indentations,)  by  the  greater  or 
less  abundance  of  the  parenchyma  in  which  the  veins  are  distrib- 
uted. This  view  is  readily  intelligible  upon  the  supposition  that  a 
leaf  is  an  expansion  of  soft  parenchyma,  in  which  the  firmer  veins 
are  variously  ramified.  Thus,  if  the  principal  veins  of  a  feather- 
veined  leaf  are  not  greatly  prolonged,  and  are  somewhat  equal  in 
length,  the  blade  will  have  a  more  or  less  elongated  form.  If  the 
veins  are  very  short  in  proportion  to  the  midrib,  and  equal  in  length, 
the  leaf  will  be  linear  (as  in  Fig.  198) ;  if  longer  in  proportion, 
but  still  equal,  the  leaf  will  assume  an  oblong  form  (Fig.  200), 
which  a  slight  rounding  of  the  sides  converts  into  an  oval  or  ellip- 
tical outline.  If  the  veins  next  the  base  are  longest,  and  espe- 
cially if  they  curve  forward  towards  their  extremities,  the  leaf 
assumes  a  lanceolate  (Fig.  197),  ovate  (Fig.  199),  or  some  inter- 
mediate form.  On  the  other  hand,  if  the  veins  are  more  developed 
beyond  the  middle  of  the  blade,  the  leaf  becomes  ohovate  (Fig. 
189),  or  cuneiform  (Fig.  192).  In  radiated  or  palmately-veined 
leaves  (Fig.  202-204),  where  the  primary  ribs  are'  divergent,  an 
orbicular  or  roundish  outline  is  most  common,  and  indeed  is  uni- 
versal when  the  ribs  are  of  equal  strength.  Some  of  the  ribs  or 
their  ramifications  being  directed  backwards,  a  recess,  or  sinus,  as 


164 


THE    LEAVES. 


it  is  termed,  is  produced  at  the  base  of  the  leaf,  which,  taken  in 
connection  with  the  general  form,  gives  rise  to  such  terms  as  cor- 
date  or  heart-shaped  (Fig.  191),  reniform  or  kidney- shaped  (Fig. 
202),  &c.,  when  the  posterior  portions  are  rounded;  and  those  of 
sagittate  or  arrow-headed  (Fig.  208),  and  hastate  or  halberd-shaped 
(Fig.  206),  when  they  are  produced  into  angles  or  lobes.  The 
margins  of  the  sinus  are  sometimes  brought  into  contact,  when 
they  are  frequently  united  ;  for  whenever  soft  cellular  parts  are  in 
close  contact  at  an  early  period  of  their  development,  they  are 
very  apt  to  cohere  and  grow  together.  In  this  case  the  leaf  be- 
comes peltate,^  or  shield-shaped  (Fig.  204) ;  the  blade  being  at- 
tached to  the  petiole,  not  by  its  apparent  base,  but  by  some  part  of 
the  lower  surface.  Two  or  three  common  species  of  Hydrocotyle 
plainly  exhibit  the  transition  from  common  radiated  leaves  into  the 
peltate  form.  Thus,  the  leaf  of  H.  Americana  (Fig.  203)  is  round- 
ish-reniform,  with  an  open  sinus  at  the  base ;  while  in  H,  inter- 
rupta  and  H.  umbellata  (Fig.  204),  the  margins  have  grown  to- 
gether so  as  to  obliterate  the  sinus,  and  an  orbicular  peltate  leaf  is 
produced.  In  nerved  leaves,  when  the  nerves  run  parallel  from 
the  base  to  the  apex,  as  in  Grasses  (Fig.  195),  the  leaf  is  necessa- 
rily linear,  or  nearly  so ;  but  when  they  are  more  divergent  in  the 


middle,  or  towards  the  base,  the  leaf  becomes  oblong,  oval,  or 
ovate,  &c.  (Fig.  201).     In  one  class  of  nerved  or  parallel-veined 


FIG.  202-210,    Forms  of  simple,  chiefly  radiated- veined  leaves. 


THEIR    FORM,    DIVISION,    ETC.  165 

leaves,  the  simple  veins  or  nerves  arise  from  a  prolongation  of  the 
petiole  in  the  form  of  a  thickened  midrib,  instead  of  the  base  of 
the  blade,  constituting  the  curvinerved  leaves  of  De  Candolle 
This  structure  is  almost  universal  in  the  Ginger  tribe,  the  Arrow 
root  tribe,  in  the  Banana,  and  other  tropical  plants ;  and  our  com 
mon  Pontederia,  or  Pickerel-weed  (Fig.  194),  affords  an  illustra 
tion  of  it,  in  which  the  nerves  are  curved  backwards  at  the  base 
so  as  to  produce  a  cordate  outline. 

281.  As  to  the  margin  and  particular  outline  of  leaves,  they  ex 
hibit  every  gradation  between  the  case  where  the  blade  is  entire 
that  is,  with  the  margin  perfectly  continuous  and  even  (as  in  Fig 
201),  and  those  where  it  is  cleft  or  divided  into  separate  portions 
The  convenient  hypothesis  of  De  Candolle  connects  these  forms 
with  the  abundance  or  scantiness  of  the  parenchyma,  compared 
with  the  divergence  and  the  extent  of  the  ribs  or  veins ;  on  the 
supposition  that,  where  the  former  is  insufficient  completely  to  fill 
up  the  framework,  lobes,  incisions,  or  toothings  are  necessarily 
produced,  extending  from  the  margin  towards  the  centre.  Thus, 
in  the  white  and  the  yellow  species  of  Water  Ranunculus,  there 
appears  to  be  barely  sufficient  parenchyma  to  form  a  thin  covering 
for  each  vein  and  its  branches  (Fig.  207,  the  lowest  leaf) ;  such 
leaves  are  said  to  be  jiliformly  dissected,  that  is,  cut  into  threads  ; 
the  nomenclature  in  all  these  cases  being  founded  on  the  conven- 
ient, but  incorrect  supposition,  that  a  leaf  originally  entire  is  cut 
into  teeth,  lobes,  divisions,  &;c.  If,  while  the  framework  remains 
the  same  as  in  the  last  instance,  the  parenchyma  be  more  abun- 
dantly developed,  as  in  fact  happens  in  the  upper  leaves  of  the 
same  species  when  they  grow  out  of  water,  and  is  shown  in  the 
same  figure,  they  are  merely  cleft  or  lohed.  If  these  lohes  grow 
together  nearly  to  the  extremity  of  the  principal  veins,  the  leaf  is 
only  toothed,  serrated^  or  crenated ;  and  if  the  small  remaining 
notches  were  filled  with  parenchyma,  the  leaf  would  be  entire. 
The  study  of  the  development  of  leaves,  however,  proves  that  the 
parenchyma  grows  and  shapes  the  outlines  of  the  organ  in  its  own 
way,  irrespective  of  the  framework,  which  is,  in  fact,  adapted  to 
the  parenchyma  rather  than  the  parenchyma  to  it.  The  principal 
terms  which  designate  the  mode  and  degree  of  division  in  simple 
leaves  may  now  be  briefly  explained,  without  further  reference  to 
this  or  any  other  theory. 

282.  A  leaf  is  said  to  be  serrate,  when  the  margin  is  beset  with 


166  THE   LEAVES. 

sharp  teeth  which  point  forwards  towards  the  apex  (Fig.  196) ; 
dentate,  or  toothed,  when  the  sharp  salient  teeth  are  not  directed 
towards  the  apex  of  the  leaf  (Fig.  200)  ;  and  crenate,  when  the 
teeth  are  rounded  (Fig.  203,  204).  A  slightly  waved  or  sinuous 
margin  is  said  to  be  repand ;  a  strongly  uneven  margin,  with  alter- 
nate rounded  concavities  and  convexities,  is  termed  sinuate  (as  in 
the  Oak).  When  the  leaf  is  irregularly  and  sharply  cut  deep  into 
the  lamina,  it  is  said  to  be  incised  ;  when  the  portions,  or  segments, 
are  more  definite,  it  is  said  to  be  lobed  ;  and  the  terms  two-lohed, 
three-lobed,  Jive-lohed,  &c.,  express  the  number  of  the  segments. 
If  the  incisions  extend  about  to  the  middle  of  the  blade,  or  some- 
what deeper,  the  leaf  is  said  to  be  cleft  ;  and  the  terms  tiuo-cleft, 
three-cleft,  &c.  (or  in  the  Latin  form,  bifd,  trifid,  &c.),  designate 
the  number  of  the  segments  :  or  when  the  latter  are  numerous  or 
indefinite,  the  leaf  is  termed  many-cleft,  or  multifid.  If  the  seg- 
ments extend  nearly,  but  not  quite,  to  the  base  of  the  blade  or  the 
midrib,  the  leaf  is  said  to  be  parted  (Fig.  209) :  if  they  reach  the 
midrib  or  the  base,  so  as  to  interrupt  the  parenchyma,  the  leaf  is 
said  to  be  divided ;  the  number  of  partitions  or  divisions  being 
designated,  as  before,  by  the  terms  two-,  three-,  five-parted,  or 
two-,  three-,  five-divided,  &c. 

283.  As  the  mode  of  division  always  coincides  with  the  arrange- 
ment of  the  primary  veins,  the  lobes  or  incisions  of  feather-veined, 
are  differently  arranged  from  those  of  radiated  or  palmately  veined 
leaves :  in  the  latter,  the  principal  incisions  are  all  directed  to  the 
base  of  the  leaf;  in  the  former,  towards  the  midrib.  These  modi- 
fications are  accurately  described  by  terms  indicative  of  the  vena- 
tion, combined  with  those  that  express  the  degree  of  division. 
Thus,  a  feather-veined  (in  the  Latin  form,  b.  pinnately  veined)  leaf 
is  said  to  be  pinnately  cleft  or  pinnatifid,  when  the  sinuses  reach 
halfway  to  the  midrib ;  pinnately  parted,  when  they  extend  al- 
most to  the  midrib  ;  and  pinnately  divided,  when  they  reach  the 
midrib,  dividing  the  parenchyma  into  separate  portions.  A  few 
subordinate  modifications  are  indicated  by  special  terms:  thus,' a 
pinnatifid  or  pinnately  parted  leaf,  with  regular,  very  close  and 
narrow  divisions,  like  the  teeth  of  a  comb,  is  said  to  be  pectinate ; 
a  feather-veined  leaf,  more  or  less  pinnatifid,  but  with  the  lobes 
decreasing  in  size  towards  the  base,  is  termed  lyrate,  or  lyre- 
shaped  {Fig.  212);  and  a  lyrate  leaf  with  sharp  lobes  pointing 
towards  the  base,  as  in  the  Dandelion  (Fig.  213),  is  called  runci- 


THEIR    FORM,    DIVISION,   ETC.  167 

nale.  A  palmately  veined  leaf  is  in  like  manner  said  to  be  pal- 
jnately  clefts  palmately  parted^  palmately  divided^  &c.  (Fig.  207, 
209),  according  to  the  degree  of  division.  The  term  palmate  was 
originally  employed  to  designate  a  leaf  more  or  less  deeply  cut 
into  about  five  spreading  lobes,  bearing  some  resemblance  to  a 
hand  with  the  fingers  spreading ;  and  it  is  still  used  to  designate  a 
palmately  lobed  leaf,  without  reference  to  the  depth  of  the  sinuses. 
A  palmate  leaf  with  the  lateral  lobes  cleft  into  two  or  more 
segments,  is  said  to  be  pedate  (Fig.  205),  from  a  fancied  resem- 
blance to  a  bird's  foot.  By  designating  the  number  of  the  lobes  in 
connection  with  the  terms  which  indicate  their  extent  and  their 
disposition,  botanists  are  enabled  to  describe  all  these  modifications 
with  great  brevity  and  precision.  Thus,  a.  palmately  Jive-parted 
leaf  is  one  of  the  radiated-veined  kind,  which  is  divided  almost  to 
the  base  into  five  segments :  a  pinnately  Jive-parted  leaf  is  one  of 
the  feather-veined  kind  cut  into  five  lobes  (two  on  each  side,  and 
one  terminal),  with  the  sinuses  extending  almost  to  the  midrib: 
and  the  same  plan  is  followed  in  describing  cleft,  lobed,  or  divided 
leaves. 

284.  The  segments  of  a  lobed  or  divided  leaf  may  be  again  di- 
vided, lobed,  or  cleft,  upon  the  same  principle  as  the  leaf  itself, 
and  the  same  terms  are  employed  in  describing  them.  Some- 
times both  the  primary,  secondary,  and  even  tertiary  divisions  are 
defined  by  a  single  word  or  phrase;  as  bipinnatifid  (Fig.  214), 
tripinnatijid,  bipimiately  parted,  tripinnately  parted,  twice  pal- 
mately parted,  &c. 

285.  Parallel-veined  or  nerved  leaves  may  be  expected  to  pre- 
sent entire  margins,  and  this  in  fact  almost  universally  occurs  when 
the  nerves  are  convergent  (Fig.  201).  Such  leaves  are  often 
lobed  or  cleft  when  the  principal  nerves  diverge  greatly,  as  in  the 
Dragon  Arum ;  but  the  lobes  themselves  are  entire.  So,  also, 
ribbed  leaves  are  mostly  entire,  when  the  ribs  converge  to  the 
apex  :  and  leaves  which  exhibit  a  well-marked  marginal  vein  (the 

falsely  ribbed  leaves  of  Lindley),  into  which  the  lateral  veinlets 
are  confluent  (as  in  all  Myrtaceous  plants),  are  also  entire. 

286.  There  are  a  few  terms  employed  in  describing  the  apex  of 
a  leaf,  which  may  be  here  enumerated.  When  a  leaf  terminates 
in  an  acute  angle,  it  is  said  to  be  acute  (Fig.  199,  208) :  when  the 
apex  is  an  obtuse  angle,  or  rounded,  it  is  termed  obtuse  (Fig.  194, 
198) :  an  obtuse  leaf,  with  the  apex  slightly  indented  or  depressed 


168  THE    LEAVES. 

in  the  middle,  is  said  to  be  refuse,  or,  if  more  strongly  notched, 
emarginate  (Fig.  188)  :  an  obovate  leaf  with  a  wider  and  more 
conspicuous  notch  at  the  apex  is  termed  obcordale  (Fig.  190), 
being  a  cordate  or  heart-shaped  leaf  inverted.  When  the  apex  is, 
as  it  were,  cut  off  by  a  straight  transverse  line,  the  leaf  is  said  to 
be  truncate :  when  abruptly  terminated  by  a  small  projecting 
point,  it  is  mucronate  (Fig.  188,  189) :  and  when  an  acute  leaf  has 
a  narrowed  and  prolonged  apex,  or  tapers  to  a  point,  it  is  acumi- 
nate, or  pointed,  as  in  Fig.  191. 

287.  All  these  terms  are  equally  applicable  to  expanded  sur- 
faces of  every  kind,  such  as  petals,  sepals,  &c.  :  and  those  terms 
which  are  used  to  describe  the  modifications  of  solid  bodies,  such 
as  stems  and  stalks,  are  equally  applicable  to  leaves  when  they 
affect  similar  shapes,  as  they  sometimes  do. 

288.  The  whole  account,  thus  far,  relates  to  Simple  Leaves, 
namely,  to  those  which  have  a  blade  of  one  piece,  however  cleft 
or  lobed,  or,  if  divided,  where  the  separate  portions  are  neither 
raised  on  stalklets  of  their  own,  nor  articulated  (by  a  joint)  with 
the  main  petiole,  so  that  the  pieces  are  at  length  detached  from  it. 
The  distinction,  however,  cannot  be  very  strictly  maintained  ;  there 
are  so  many  transitions  between  simple  and 

289.  Compound  Leaves  (Fig.  211,  215-221).  These  have  the 
blade  divided  into  entirely  separate  pieces ;  or,  rather,  they  con- 
sist of  a  number  of  blades,  borne  on  a  common  petiole,  usually 
supported  on  stalklets  of  their  own,  between  which  and  the  main 
petiole  an  articulation  or  joint  is  formed,  more  or  less  distinctly. 
These  separate  blades  are  called  Leaflets  :  they  present  all  the 
diversities  of  form,  outline,  or  division,  which  simple  leaves  ex- 
hibit ;  and  the  same  terms  are  employed  in  characterizing  them. 
Having  the  same  nature  and  origin  as  the  lobes  or  segments  of 
simple  leaves,  they  are  arranged  in  the  same  ways  on  the  common 
petiole.  Compound  leaves  accordingly  occur  under  two  general 
forms,  the  pinnate,  and  the  palmate,  otherwise  called  digitate. 
The  pinnate  form  is  produced  when  a  leaf  of  the  pinnately  veined 
sort  becomes  compound  ;  that  is,  the  leaflets  are  situated  along  the 
sides  of  the  common  petiole.  There  are  several  modifications  of 
the  pinnate  leaf.  It  is  abruptly  pinnate,  when  the  leaflets  are 
even  in  number,  and  none  is  borne  on  the  very  apex  of  the  petiole 
or  its  branches,  as  in  Cassia  ;  and  also  in  the  Vetch  tribe,  where, 
however,  the  apex  of  the  petiole  is  generally  prolonged  into  a  ten- 


THEIR    FORM,    DIVISION,    ETC. 


169 


dril  (Fig.  216).  It  is  impari-pinnate,  or  pinnate  with  an  odd  leaf- 
let, when  the  petiole  is  terminated  with  a  leaflet  (Fig.  215,  220). 
There  are  some  subordinate  modifications ;  such  as  lyrately  pin- 
nate^ when  the  blade  of  a  lyrate  leaf  (Fig.  212)  is  completely  di- 
vided, as  in  Fig.  220 ;  and  interruptedly  pinnate^  when  some  mi- 
nute leaflets  are  irregularly  intermixed  with  larger  ones,  as  is  also 
shown  to  some  extent  in  the  figure  last  cited.  The  number  of 
leaflets  varies  from  a  great  number  to  very  few.  When  reduced  to 
a  small  number,  such  a  leaf  is  said  to  be  pinnately  seven-.  Jive-,  or 
tri-foliolate,  as  the  case  may  be.  A  pinnate  leaf  of  three  or  five 
leaflets  is  often  called  ternate,  or  quinate  ;  which  terms,  however, 
are  equally  applied  to  a  palmately  compound  leaf,  and  also,  and 
more  appropriately,  to  the  case  of  three  or  five  simple  leaves 
growing  on  the  same  node.  A  pinnately  trifoliolate  leaf  (Fig. 
221)   is  readily  distinguished   by  having  the  two  lateral  leaflets 


attached  to  the  petiole  at  some  distance  below  its  apex,  and  by  the 
joint  which  is  observable  at  some  point  between  their  insertion  and 
the  lamina  of  the  terminal  leaflet.  Such  a  leaf  may  even  be  re- 
duced to  the  paradoxical  case  of  a  single  leaflet ;  as  in  the  Orange 
(Fig.  218),  and  frequently  in  one  variety  of  Rhynchosia  tomen- 


FIG.  211  -  221.    Compound  and  lobed  leaves. 

15 


170  '  THE    LEAVES. 

tosa ;  which  is  distinguished  from  a  really  simple  leaf  by  the  joint 
at  the  junction  of  the  partial  with  the  general  petiole. 

290.  The  palmate  or  digitate  form  is  produced  when  a  leaf  of 
the  palmately  veined  sort  becomes  compound ;  in  which  case  the 
leaflets  are  necessarily  all  attached  to  the  apex  of  the  common 
petiole,  as  in  the  Horsechestnut  and  Buckeye  (Fig.  211).  Such 
leaves  of  three,  five,  or  any  definite  number  of  leafiets  are  termed 
palmately  (or  digitately)  trifoliolate^  jive-foUolate^  &c.  A  leaf  of 
two  leaflets,  which  rarely  occurs,  is  unijugate  (one-paired)  or  hi- 
nate.  By  this  nomenclature,  the  distinction  between  pinnately  and 
palmately  compound  leaves  is  readily  kept  up. 

291.  The  stalk  of  a  leaflet  is  called  a  partial  petiole  (petiolula) ; 
and  the  leaflet  thus  supported  is  petiolulate. 

292.  The  partial  petioles  may  bear  a  set  of  leaflets  instead  of  a 
single  one,  when  the  leaf  becomes  doubly  or  twice  compound. 
Thus  a  pinnate  leaf  again  compounded  in  the  same  way  becomes 
hipinnate^  or  if  still  a  third  time  divided  it  is  tripinnate,  &c.  In 
these  cases  the  main  divisions  or  branches  of  the  common  petiole 
are  called  piniKE.  So  a  trifoliolate  leaf  twice  compound  becomes 
hiternate ;  or  thrice,  <ri7erwa/e,  &c.  When  the  primary  division 
is  digitate,  the  secondary  division  is  often  pinnate,  thus  combining 
the  two  modes  in  the  same  leaf.  A  leaf  irregularly  or  indeter- 
minately several  times  compounded,  in  whatever  mode,  is  decom- 
pound. 

293.  The  blade  of  a  leaf  is  almost  always  symmetrical,  that  is, 
the  portions  on  each  side  of  the  midrib  or  axis  are  similar  ;  but  oc- 
casionally one  side  is  more  developed  than  the  other,  when  the  leaf 
is  oblique^  as  is  strikingly  the  case  in  the  species  of  Begonia  (Fig. 
210),  now  common  in  gardens. 

294.  The  blade  is  also  commonly  horizontal,  presenting  one 
surface  to  the  sky,  and  the  other  to  the  earth ;  in  which  case  the 
two  surfaces  differ  in  structure  (262)  as  well  as  in  appearance, 
each  being  fitted  for  its  peculiar  offices  :  if  artificially  reversed, 
they  spontaneously  resume  their  natural  position,  or  soon  perish  if 
prevented  from  doing  so.  But  in  erect  and  vertical  leaves,  the 
two  surfaces  are  equally  exposed  to  the  light,  and  are  similar  in 
structure  and  appearance.  In  such  erect  leaves  as  those  of  Iris,  it 
is  what  corresponds  to  the  lower  surface  of  ordinary  leaves  that  is 
presented  to  the  air ;  for  the  leaf  is  folded  together  lengthwise  and 
consolidated  while  in  the  nascent  state,  so  that  the  true  upper  sur- 


THEIR    FORM,    DIVISION,    ETC. 


171 


face  is  concealed  in  ihe  interior,  except  near  the  base,  where  they 
override  each  other  in  the  equitant  manner  (258).  True  vertical 
leaves,  which  present  their  edges  instead  of  their  surfaces  to  the 
earth  and  sky,  generally  assume  this  position  by  a  twisting  of  the 
base  or  of  the  petiole ;  as  is  strikingly  seen  in  a  large  number  of 
New  Holland  trees  of  the  Myrtle  Family,  now  common  in  green- 
houses. 

295.  Leaves  assume  extraordinary  appearances  when  they  be- 
come succulent,  as  in  the  different  species  of  Mesembryanthemum 
(Ice-plant),  &c.,  and  no  less  so  when,  on  the  contrary,  producing 
little  or  no  green  parenchyma,  they  become  scale-like,  as  in  Beech- 
drops,  Monotropa,  and  other  parasitic  plants ;  where  they  do  not 
perform  the  ordinary  office  of  leaves.  Not  unlike  these  are  the 
altered  or  degenerate  leaves  that  form  the  in- 
teguments of  scaly  buds  (146).  The  primary 
leaves  on  every  shoot  of  the  Pine  are  merely 
thin  and  dry  scales ;  from  the  axils  of  which 
the  ordinary  foliage  is  developed  in  fascicles 
of  needle-shaped  leaves  (253). 

296.  Leaves  which  grow  under  water  are 
often  nearly  or  quite  destitute  of  parenchyma  ; 
as  in  Ranunculus  Purshii  (Fig.  207),  and  Ra- 
nunculus aquatilis,  Bidens  Beckii,  Myriophyl- 
lum,  &c.  A  very  remarkable  instance  of  the 
kind  occurs  in  Ouvirandra  fenestralis,  a  South 
African  aquatic  plant,  with  nerved  leaves, 
which  exhibit  a  complete  framework  or  skel- 
eton, while  the  parenchyma  is  entirely  want- 
ing. In  the  Barberry  some  of  the  summer 
leaves  harden  as  they  grow  into  compound  or 
branching  spines  (Fig.  222). 

297.  When  the  blade  of  the  leaf  is  want- 
ing, its  office  is  sometimes  performed  by  the 
petiole,  or  by  the  stipules. 

298.  The  Petiole,  or  Leafstalk,  is  usually  either  round,  or  half- 
cylindrical  and  channelled  on  the  upper  side.  But  in  the  Aspen, 
it  is  strongly  flattened  at  right  angles  with  the  blade,  so  that  the 
slightest  breath  of  air  puts  the  leaves  in  motion.     It  is  not  unfre- 


FIG.  222.     A  summer  shoot  of  the  Barberry,  showing  a  lower  leaf  in  the  normal  state;  the 
next  partially,  those  still  higher  completely,  transformed  into  spines. 


172 


THE    LEAVES. 


quently  furnished  with  a  leaf-like  border,  or  wing ;  which,  in  the 
Sweet  Pea  of  the  gardens,  extends  downward  along  the  stem,  on 
which  the  leaves  are  then  said  to  be  decurrent ;  or  the  stalk  or 
stem  thus  bordered  is  said  to  be  alate  or  winged.  In  many  Um- 
belliferous plants,  the  base  of  the  petiole  is  dilated  into  a  broad  and 
membranaceous  inflated  sheath  ;  and  in  a  great  number  of  Endoge- 
nous plants,  especially  in  Grasses,  the  petiole  consists  of  a  sheath^ 
embracing  the  stem,  which  in  the  true  Grasses  is  furnished  at  the 
summit  with  a  membranous  appendage,  in  some  sort  equivalent  to 
the  stipules,  called  the  ligule  (Fig.  195).  In  the  proper  Pea  tribe, 
the  apex  of  the  petiole  is  often  changed  into  a  tendril  (Fig.  216) ; 
and  in  one  plant  of  that  tribe  (Lathyrus  Aphaca),  the  whole  petiole 
becomes  a  tendril,  the  office  of  the  leaf  being  fulfilled  by  a  pair  of 
large  stipules.  Sometimes,  as  in  one  section  of  Astragalus,  the 
petioles  harden  into  spines  after  the  leaflets  fall  off". 

299.  The  woody  and  vascular  tissue  runs  lengthwise  through 
the  petiole,  in  the  form  usually  of  a  definite  number  of  parallel 
threads,  to  be  ramified  in  the  blade.  The  ends  of  these  threads  are 
apparent  on  the  base  of  the  leafstalk  when  it  falls  off,  and  on  the 
scar  left  on  the  stem,  as  so  many  round  dots  (Fig.  130,  127,  Z>),  of 
a  uniform  number  and  arrangement  in  each  species.  Sometimes 
they  are  so  close  as  to  be  confluent  into  a  continuous  line  or  bundle. 


300.  Phyllodia  (Fig.  226,  227).     Occasionally  the  woody  sys- 
tem spreads  and  the  whole  petiole  dilates  into  a  kind  of  blade, 

FIG.  223.     Pitchers  of  Heliamphora;  224,  of  Sarracenia  purpurea ;  225,  of  Nepenthes.    226. 
A  phyllodium  of  a  New  Holland  Acacia.    227.  The  same,  bearing  a  reduced  compound  blade. 


PHYLLODIA,   ASCIDIA,   ETC. 


173 


traversed  by  ribs,  mostly  of  the  parallel-veined  kind.  In  these 
cases  the  proper  blade  of  the  leaf  is  connmonly  abortive  or  disap- 
pears ;  this  substitute,  called  a  Phyllodium  (meaning  a  leaf-like 
body),  taking  its  place.  These  phyllodia  constitute  the  whole  foli- 
age of  the  numerous  Australian  Acacias.  Here  they  are  at  once 
distinguished  from  leaves  with  a  true  blade  by  being  entire  and 
parallel-veined  ;  while  their  proper  leaves,  as  the  primordial  ones 
uniformly  appear  in  germination,  and  also  later  ones  in  casual  in- 
stances, are  compound  and  netted-veined.  They  are  also  recog- 
nized by  their  uniformly  vertical  position,  presenting  their  margins 
instead  of  their  surfaces  to  the  earth  and  sky ;  and  they  sometimes 
bear  a  true  compound  lamina  at  the  apex,  as  in  Fig.  227.  These 
Acacias,  with  the  Myrtaceous  trees  that  have  leaves  with  a  proper 
blade  which  becomes  vertical  by  a  twist  (294),  compose  more  than 
half  of  the  forests  of  New 
Holland,  and  give  to  them  a 
prevailing  and  very  peculiar 
feature,  and  an  unusual  dis- 
tribution of  light  and  shade  ; 
the  cause  of  which  was  de- 
tected by  the  scrutinizing 
glance  of  Robert  Brown. 

301.  In  the  Dionsea,  or 
Venus's  Fly-catcher,  (Fig. 
228,)  the  proper  lamina,  or 
blade  of  the  leaf,  is  the  ter- 
minal portion,  fringed  with 
stiff  bristles,  which  closes 
suddenly  and  with  consider- 
able force  when  the  upper 
surface  is  touched.  This  is 
borne  on  a  dilated,  foliaceous 
body,  which  may  be  held 
to  represent  the  petiole ;  but 
it  is  horizontally  expanded 
and  netted-veined.  Still  more  singular  modifications  of  the  leaf  are 
met  with  in  the  form  of 

302.  Ascidia,  or  Pitchers  (Fig.  223-225).     These  occur  in  sev- 


FIG.  228.    A  plant  of  Dionaea  muscipula,  reduced  in  size. 

15* 


174 


THE    LEAVES. 


eral  plants  of  widely  different  families.  If  we  conceive  the  mar- 
gins of  the  dilated  petiole  of  Dionaea  to  curve  inwards  until  they 
meet,  and  cohere  with  each  other,  there  would  result  a  leaf  not 
unlike  that  of  Sarracenia  purpurea,  the  common  Pitcher-plant  or 
Sidesaddle  Flower  of  the  Northern  United  States  (Fig.  224),  in 
which,  accordingly,  the  tube  or  pitcher  may  be  considered  as  the 
petiole,  and  the  hood  at  the  summit  as  the  lamina.  This  view  is 
confirmed  by  a  new  Pitcher-plant  of  the  same  family  ( Heliampho- 
ra.  Fig.  223),  recently  discovered  by  Mr.  Schomburgk  in  the 
mountains  of  British  Guiana,  and  described  by  Mr.  Bentham  ;  in 
which  the  margins  of  the  dilated  petiole  are  not  always  united 
quite  to  the  summit,  and  the  lamina  is  represented  by  a  small 
concave  terminal  appendage.  In  the  curious  Nepenthes  (Fig. 
225),  the  petiole  is  first  dilated  into  a  kind  of  lamina,  then  con- 
tracted into  a  tendril,  and  finally  dilated  into  a  pitcher,  contain- 
ing fluid  secreted  by  the  plant  itself;  the  orifice  being  accurately 
closed  by  a  lid,  which  is  from  analogy  supposed  to  represent  the 
real  blade  of  the  leaf. 

303.  The  cohesion  of  the  edges  of  a  leaf  with  each  other,  or 
with  neighbouring  organs,  is  by  no  means  infrequent ;    since  all 

parts  or  organs  of  a  plant  which  are  contigu- 
ous at  the  time  of  their  development  are  liable 
to  become  ingrafted  or  to  cohere  together. 
This  is  illustrated  by  the  formation  of  peltate 
leaves  (Fig.  203,  204),  and  likewise  by  what 
are  termed  perfoliate  leaves  ;  whether  formed 
by  the  union  of  the  bases  of  a  pair  of  opposite 
sessile  leaves  (connate-perfoUate),  as  in  Sil- 
phium  perfoliatum,  Triosteum  perfoliatum, 
the  upper  pairs  of  the  Honeysuckle,  &;c. ;  or 
consisting  of  a  single  clasping  leaf,  the  pos- 
terior lobes  of  which  encompass  the  stem  and 
cohere  on  the  opposite  side,  as  is  seen  in 
Bupleurum  rotundifolium,  Uvularia  perfoliata, 
and  Baptisia  perfoliata  (Fig.  229). 

304.  Stipules  (259)  are  lateral  appendages  of  leaves,  usually  in 
the  form  of  small  foliaceous  bodies,  situated  on  each  side  of  the 
base  of  the  petiole  (Fig.  215,  &c.).     They  are  not  found  at  all  in  a 


FIG.  229.    Perfoliate  leaves  of  Baptishi  perfoliata. 


STIPULES.  175 

great  number  of  plants ;  but  their  presence  or  absence  is  usually 
uniform  throughout  each  natural  order.  They  commonly  have  the 
texture,  color,  and  venation  of  leaves,  and  are  subject  to  similar 
modifications.  Like  leaves,  they  are  sometimes  membranaceous 
or  scale-like,  and  sometimes  transformed  into  spines,  &c. ;  and  they 
have  also  a  strong  tendency  to  cohere  with  each  other,  or  with  the 
base  of  the  petiole.  Thus,  in  the  Clover,  the  Strawberry,  and  the 
Rose  (Fig.  215),  a  stipule  adheres  to  each  side  of  the  base  of  the 
petiole ;  in  the  Plane-tree,  they  are  free  from  the  petiole,  but  co- 
here by  their  outer  margins,  so  as  to  form  an  apparently  single 
stipule  opposite  the  leaf.  In  other  cases,  both  margins  are  united, 
forming  a  sheath  around  the  stem,  just  above  the  leaf :  these  are 
called  intrafoliaceous  stipules,  or,  when  membranaceous,  as  in  Po- 
lygonum (see  Ord.  Polygonacese),  they  have  been  termed  ochrece. 
When  opposite  leaves  have  stipules,  which  is  not  very  common, 
they  usually  occupy  the  space  between  the  petioles  on  each  side, 
and  are  termed  interpetiolar.  The  stipules  of  each  leaf  (one  on 
each  side),  being  thus  placed  in  contact,  frequently  unite,  so  as  to 
form  apparently  but  a  single  pair  of  stipules  for  each  pair  of 
leaves ;  instances  of  which  are  very  common  in  the  order  Ru- 
biacesB. 

305.  When  leaves  are  furnished  with  stipules,  they  are  said  to 
be  stipulate :  when  destitute  of  these  appendages,  exstipulate. 
They  are  sometimes  present  in  young  leaves  only  ;  as  in  the 
Beech,  the  Fig,  and  the  Magnolia  (Fig.  130,  131),  where  they 
form  the  covering  of  the  buds,  but  fall  away  as  these  expand. 

306.  The  leaflets  of  compound  leaves  are  sometimes  provided 
with  small  stipules  (stipeUes)  of  their  own,  as  in  the  Bean  (Fig. 
221) ;  when  they  are  said  to  be  stipellate. 

Sect.  III.     The  Death  and  Fall  of  the  Leaves  ;    Exhala- 
tion, ETC. 

307.  While  the  axis,  or  portion  of  each  phyton  that  belongs  to 
the  stem,  is  permanent  during  the  life  of  the  individual  plant,  the 
leaf  lasts  only  for  a  limited  period,  and  is  thrown  off,  or  perishes 
and  decays,  after  having  fulfilled  its  temporary  ofliice. 

308.  Duration  of  LeaYCS.  In  view  of  their  duration,  leaves  are 
called  fugacious,  when  they  fall  off  soon  after  their  first  appear- 
ance ;  deciduous,  when  they  last  only  for  a  single  season ;  and 


176  THE    LEAVES. 

persistent,  when  they  remain  through  the  cold  season,  or  other 
interval  during  which  vegetation  is  interrupted,  and  until  after  the 
appearance  of  new  leaves,  so  that  the  stem  is  never  leafless ;  as 
in  Evergreens. 

309.  Leaves  last  for  a  single  year  only  in  many  Evergreens,  as 
well  as  in  deciduous-leaved  plants;  the  old  leaves  falling  soon 
after  those  of  the  ensuing  season  are  expanded,  or,  if  they  remain 
longer,  ceasing  to  bear  any  active  part  in  the  economy  of  the  veg- 
etable, and  soon  losing  their  vitality  altogether.  In  Pines  and 
Firs,  however,  as  in  many  other  evergreen  trees  and  shrubs,  al- 
though there  is  an  annual  fall  of  leaves  while  the  growth  of  the 
season  is  taking  place,  yet  these  were  the  produce  of  some  season 
earlier  than  the  last;  and  the  branches  are  continually  clothed 
with  the  foliage  of  from  two  to  five,  or  even  eight  or  ten  succes- 
sive years.  On  the  other  hand,  it  is  seldom  that  all  the  leaves  of 
an  herb  endure  through  the  whole  growing  season,  but  the  earlier 
foliage  near  the  base  of  the  stem  perishes  and  falls,  while  fresh 
leaves  are  still  appearing  at  the  summit.  In  our  deciduous  trees 
and  shrubs,  however,  the  leaves  of  the  season  are  mostly  de- 
veloped within  a  short  period,  and  they  all  perish  nearly  at  the 
same  time.  They  are  not  destroyed  by  frost,  as  is  commonly 
supposed  ;  for  they  begin  to  languish,  and  often  assume  their  au- 
tumnal tints  (as  happens  with  the  Red  Maple  especially),  or  even 
fall,  before  the  earlier  frosts ;  and  when  vernal  vegetation  is  de- 
stroyed by  frost,  the  leaves  blacken  and  wither,  but  do  not  fall  off 
entire,  as  in  autumn.  Some  leaves  are  cast  off,  indeed,  while 
their  tissues,  at  least  at  .the  base  of  the  petiole,  have  by  no  means 
lost  their  vitality.  Death  is  often  rather  a  consequence  than  the 
cause  of  the  fall.  Others  die  and  decay  on  the  stem  without  fall- 
ing, as  in  Palms  and  most  Endogens ;  or  else  the  dead  leaves  may 
hang  on  the  branches  through  the  winter,  as  in  the  Beech  and 
some  kinds  of  Oak,  to  fall  when  the  new  buds  expand,  the  follow- 
ing spring.  We  must  therefore  distinguish  between  the  death  and 
the  fall  of  the  leaf. 

310.  The  Fall  of  the  leaf  is  owing  to  an  organic  separation, 
through  an  articulation,  or  joint,  which  forms  between  the  base  of 
the  petiole  and  the  surface  of  the  stem  on  which  it  rests.  The 
formation  of  the  articulation  is  a  vital  process,  a  kind  of  disintegra- 
tion of  a  transverse  layer  of  cells,  which  cuts  off  the  petiole  by  a 
regular  line,  in  a  perfectly  uniform  manner  in  each  species,  leav- 


THEIR  DEATH  AND  FALL.  177 

ing  a  clean  scar  (Fig.  127,  130)  at  the  insertion.  The  solution  of 
continuity  begins  in  the  epidermis,  where  a  faint  line  marks  the 
position  of  the  future  joint  while  the  leaf  is  still  young  and  vigor- 
ous :  later  the  line  of  demarcation  becomes  well  marked,  internally 
as  well  as  externally ;  the  disintegrating  process  advances  from 
without  inwards  until  it  reaches  the  woody  bundles ;  and  the  side 
next  the  stem,  which  is  to  form  the  surface  of  the  scar,  has  a 
layer  of  cells  condensed  into  what  appears  like  a  prolongation 
of  the  epidermis,  so  that,  when  the  leaf  separates,  "  the  tree 
does  not  suffer  from  the  effects  of  an  open  wound."  "  The  pro- 
vision for  the  separation  being  once  complete,  it  requires  little  to 
effect  it;  a  desiccation  of  one  side  of  the  leafstalk,  by  causing 
an  effort  of  torsion,  will  readily  break  through  the  small  remains  of 
the  fibro-vascular  bundles ;  or  the  increased  size  of  the  coming 
leaf- bud  will  snap  them ;  or,  if  these  causes  are  not  in  operation, 
a  gust  of  wind,  a  heavy  shower,  or  even  the  simple  weight  of  the 
lamina,  will  be  enough  to  disrupt  the  small  connections  and  send  the 
suicidal  member  to  its  grave.  Such  is  the  history  of  the  fall  of  the 
leaf.  We  have  found  that  it  is  not  an  accidental  occurrence,  aris- 
ing simply  from  the  vicissitudes  of  temperature  and  the  like,  but  a 
regular  and  vital  process,  which  commences  with  the  first  formation 
of  the  organ,  and  is  completed  only  when  that  is  no  longer  useful ; 
and  we  cannot  help  admiring  the  wonderful  provision  that  heals 
the  wound  even  before  it  is  absolutely  made^  and  affords  a  covering 
from  atmospheric  changes  before  the  part  can  be  subjected  to 
them."  *  Leaves  fall  by  an  articulation  in  most  Exogenous  plants, 
where  the  insertion  usually  occupies  only  a  moderate  part  of  the 
circumference  of  the  stem,  and  especially  in  those  with  woody 
stems  which  continue  to  increase  in  diameter.  When  they  are 
not  cast  off  in  autumn,  therefore,  the  disruption  inevitably  takes 
place  the  next  spring,  or  whenever  the  circumference  further  en- 
larges. But  in  most  Endogenous  plants,  where  the  leaves  are 
scarcely,  if  at  all,  articulated  with  the  stem,  which  increases  little 
in  diameter  subsequently  to  its  early  growth,  they  are  not  thrown 
off,  but  simply  wither  and  decay  ;  their  dead  bases  or  petioles  being 
often  persistent  for  a  long  time. 

311.  The  Death  of  the  Leaf,  however,  in  these  and  other  cases,  is 
still  to  be  explained.     Why  have  leaves  such  a  temporary  exist- 

*  Dr.  Inman,  in  Henfrey's  Botanical  Gazette,  1.  p.  61. 


178 


THE    LEAVES. 


ence  ?  Why  in  ordinary  cases  do  they  last  only  for  a  single  year, 
or  a  single  summer  ?  The  answer  to  this  question  is  to  be  found 
in  the  anatomical  structure  of  the  leaf,  and  the  nature  and  amount 
of  the  fluid  which  it  receives  and  exhales.  The  water  continually 
absorbed  by  the  roots  dissolves,  as  it  percolates  the  soil,  a  small 
portion  of  earthy  matter.  In  limestone  districts  especially,  it  takes 
up  a  sensible  quantity  of  carbonate  and  sulphate  of  lime,  and  be- 
comes hard.  It  likewise  dissolves  a  smaller  proportion  of  silex, 
magnesia,  potash,  &c.  A  part  of  this  mineral  matter  is  at  once 
deposited  in  the  woody  tissue  of  the  stem  (210) ;  but  a  larger  por- 
tion is  carried  into  the  leaves  (40,  92),  where,  as  the  water  is  ex- 
haled or  distilled  perfectly  pure,  all  this  earthy  substance  must  be 
left  behind  to  incrust  the  delicate  cells  of  the  parenchyma,  much  as 
the  vessels  in  which  water  is  boiled  for  culinary  purposes  are  in  time 
incrusted  with  an  earthy  deposit.  This  earthy  incrustation,  in  con- 
nection with  the  deposition  of  organic  solidified  matter  (39),  gradu- 
ally chokes  the  tissue  of  the  leaf,  obstructs  the  exhalation,  and 
finally  unfits  it  for  the  performance  of  its  offices.  Hence  the  fresh 
leaves  most  actively  fulfil  their  functions  in  spring  and  early  sum- 
mer ;  but  languish  towards  autumn,  and  ere  long  inevitably  perish. 
Hence,  although  the  roots  and  branches  may  be  permanent,  the 
necessity  that  the  leaves  should  be  annually  renewed.  But  the 
former  are,  in  fact,  annually  renewed  likewise  ;  and  life  abandons 
the  annual  layers  of  wood  and  bark  almost  as  soon  as  it  does  the 
leaves  they  supply  (216,  217,  228),  and  for  similar  reasons  ;  al- 
though their  situation  is  such  that  they  become  part  of  a  perma- 
nent structure,  and  serve  to  convey  the  sap  even  when  no  longer 
endowed  with  vitality. 

312.  The  general  correctness  of  this  view  may  be  tested  by  di- 
rect microscopical  observation.  In  Fig.  185,  186,  some  superficial 
parenchyma  thus  obstructed  by  long  use  is  represented ;  and  sim- 
ilar illustrations  may  be  obtained  from  ordinary  leaves.  That  this 
deposit  consists  nn  great  part  of  earthy  matter  is  shown  by  care- 
fully burning  away  the  organic  materials  of  an  autumnal  leaf  over 
a  lamp,  and  examining  the  ashes  by  the  microscope  ;  which  will  be 
found  very  perfectly  to  exhibit  the  form  of  the  cells.  The  ashes 
which  remain  when  a  leaf  or  other  vegetable  substance  is  burned 
in  the  open  air  represent  the  earthy  materials  which  it  has  accu- 
mulated. A  vernal  leaf  leaves  only  the  minutest  quantity  of  ash- 
es ;  an  autumnal  leaf  yields  a  very  large  proportion  ;  from  ten  to 


EXHALATION    AND   THE    RISE    OF    THE    SAP.  179 

thirty  times  as  much  as  the  wood  of  the  same  species ;  although 
the  leaves  contain  the  deposit  of  a  single  season  only,  while  the 
heart-wood  is  loaded  with  the  accumulations  of  successive  years.* 

313.  Exhalation  from  the  leaves.  The  quantity  of  water  exhaled 
.from  the  leaves  during  active  vegetation  is  very  great.  In  one  of 
the  well-known  experiments  of  Hales,  a  Sunflower  three  and  a 
half  feet  high,  with  a  surface  of  5,616  square  inches  exposed  to 
the  air,  was  found  to  perspire  at  the  rate  of  twenty  to  thirty  ounces 
avoirdupois  every  twelve  hours,  or  seventeen  times  more  than  a 
man.  A  vine,  with  twelve  square  feet  of  foliage,  exhaled  at  the 
rate  of  five  or  six  ounces  a  day ;  and  a  seedling  Apple-tree,  with 
eleven  square  feet  of  foliage,  lost  nine  ounces  a  day.  The  amount 
varies  with  the  degree  of  warmth  and  dryness  of  the  air,  and  of  ex- 
posure to  light ;  and  is  also  very  different  in  different  species,  some 
exhaling  more  copiously  even  than  the  Sunflower.  But  when  we 
consider  the  vast  perspiring  surface  presented  by  a  large  tree  in  full 
leaf,  it  is  evident  that  the  quantity  of  watery  vapor  it  exhales  must 
be  immense.  This  exhalation  is  dependent  on  the  capacity  of  the 
air  for  moisture  at  the  time,  and  upon  the  presence  of  the  sun  ; 
often  it  is  scarcely  perceptible  during  the  night.  The  Sunflower, 
in  the  experiment  of  Hales,  lost  only  three  ounces  in  a  warm,  dry 
night,  and  underwent  no  diminution  during  a  dewy  night. 

314.  Rise  of  the  Sap.  Now  this  exhalation  by  the  leaves  requires 
a  corresponding  absorption  by  the  roots.  The  one  is  the  measure 
of  the  other.  If  the  leaves  exhale  more  in  a  given  time  than  the 
roots  can  restore  by  absorption  from  the  soil,  the  foliage  droops  ; 
as  we  see  in  a  hot  and  dry  summer  afternoon,  when  the  drain  by 
exhalation  is  very  great,  while  a  further  supply  of  moisture  can 
hardly  be  extorted  from  the  parched  soil ;  —  as  we  observe  also  in 
a  leafy  plant  newly  transplanted,  where  the  injured  rootlets  are  not 
immediately  in  a  fit  condition  for  absorption.  Ordinarily,  how- 
ever, exhalation  by  the  leaves  and  absorption  by  the  roots  are  in 
direct  ratio  to  each  other,  and  the  loss  sustained  by  the  leaves  is 

*  The  dried  leaves  of  the  Elm  contain  more  than  eleven  per  cent,  of  ashes,, 
while  the  wood  contains  less  than  two  per  cent. ;  those  of  the  Willow,  more 
than  eight  per  cent.^  while  the  wood  has  only  0.45 ;  those  of  the  Beech,  6.69, 
the  wood  only  0.36;  those  of  the  (European)  Oak,  4.05,  the  wood  only  0.21  ; 
those  of  the  Pitch-Pine,  3.15,  the  wood  only  0.25  per  cent.  Hence  the  decay- 
ing foliage  in  our  forests  restores  to  the  soil  a  large  proportion  of  the  inorganic 
matter  which  the  trees  from  year  to  year  take  from  it. 


180 


THE    LEAVES. 


immediately  restored  (by  endosmosis,  37)  through  the  ascent  of 
the  sap  from  the  branches,  the  latter  being  constantly  supplied  by 
the  stem  ;  so  that,  during  active  vegetation,  the  sap  ascends  from 
the  remotest  rootlets  to  the  highest  leaves,  with  a  rapidity  corre- 
sponding to  the  amount  of  exhalation.  The  action  of  the  leaves  is, 
therefore,  the  principal  mechanical  cause  of  the  ascent  of  the  sap. 
This  is  beautifully  illustrated  when  a  graft  has  a  different  time  of 
leafing  from  that  of  the  stock  upon  which  it  is  made  to  grow,  the 
graft  wholly  regulating  the  season  or  temperature  at  which  the  sap 
is  put  in  motion,  and  controlling  the  habits  of  the  original  stock. 
Also  by  introducing  the  branches  of  a  tree  into  a  conservatory 
during  winter ;  when,  as  their  buds  expand,  the  sap  in  the  trunk 
without  is  set  unseasonably  into  motion  to  supply  the  demand. 

315.  During  the  summer's  vegetation,  while  the  sap  is  consumed 
or  exhaled  almost  as  fast  as  it  enters  the  plant,  no  considerable 
accumulation  can  take  place  :  but  in  autumn,  when  the  leaves  per- 
ish, the  rootlets,  buried  in  the  soil  beyond  the  influence  of  the  cold, 
which  checks  all  vegetation  above  ground,  continue  for  a  time 
slowly  to  absorb  the  fluid  presented  to  them.  Thus  the  trunks  of 
many  trees  are  at  this  season  gorged  with  sap,  which  will  flow 
from  incisions  made  into  the  wood.  This  sap  undergoes  a  gradual 
change  during  the  winter,  and  deposits  its  solid  matter  in  the  tubes 
and  cells  of  the  wood.  The  absorption  recommences  in  the 
spring,  before  new  leaves  are  expanded  to  consume  the  fluid ;  the 
soluble  matters  in  the  tissue  of  the  stem  are  redissolved,  and  the 
trunk  is  consequently  again  gorged  with  sap,  which  will  flow,  or 
bleed,  when  wounded.  But  when  the  leaves  resume  their  func- 
tions, or  when  flowers  are  developed  before  the  leaves  appear,  as 
in  many  forest-trees,  this  stock  of  rich  sap  is  rapidly  consumed, 
and  the  sap  will  no  longer  flow  from  an  incision.  It  is  not,  there- 
fore, at  the  period  when  the  trunk  is  most  gorged  with  sap,  in 
spring  and  autumn,  but  when  least  so,  during  summer,  that  the  sap 
is  probably  most  rapidly  ascending. 


PHYSIOLOGY    OF    VEGETATION.  181 

CHAPTER    YI. 

OF    THE    FOOD    AND    NUTRITION    OF    PLANTS. 

Sect.  I.     The  General  Physiology  of  Vegetation. 

316.  The  Organs  of  Vegetation  or  Nutrition  (those  by  which 
plants  grow  and  form  their  various  products)  having  now  been 
considered,  both  separately  and  to  some  extent  in  their  combined 
action,  we  are  prepared  to  take  a  comprehensive  survey  of  the 
general  phenomena  and  results  of  vegetation ;  to  inquire  into  the 
elementary  composition  of  plants,  the  nature  of  the  food  by  which 
they  are  nourished,  the  sources  from  which  this  food  is  derived, 
and  the  transformations  it  undergoes  in  their  system,  chiefly  in  the 
leaves.  It  is  in  vegetable  digestion,  or,  to  use  a  better  term,  in 
assimilation^  that  the  essential  nature  of  vegetation  is  to  be  sought, 
since  it  is  in  this  process  alone  that  mineral,  unorganized  matter  is 
converted  into  the  tissue  of  plants  and  other  forms  of  organized 
matter  (12,  15,  16).  From  this  point  of  view,  therefore,  the  re- 
ciprocal relations  and  influences  of  the  mineral,  vegetable,  and 
animal  kingdoms  may  be  most  advantageously  contemplated,  and 
the  office  of  plants  in  the  general  economy  of  the  world  best  under- 
stood. This  portion  of  general  physiology  is  intimately  connected 
with  chemistry,  and  some  knowledge  of  that  science  is  requisite  for 
the  due  comprehension  of  the  subject,  especially  in  relation  to  its 
exceedingly  important  applications  to  agriculture  and  horticulture. 
We  are  here  restricted  to  the  bare  statement  of  the  leading  facts 
which  are  thought  to  be  established,  and  the  more  important  de- 
ductions which  may  be  drawn  from  them  ;  omitting,  for  the  most 
part,  to  adduce  the  evidence  by  which  these  general  propositions 
are  supported. 

317.  Although  the  organs  of  vegetation  have  been  considered 
anatomically  and  morphologically,  or  in  view  of  their  structure 
and  development,  still  the  leading  points  of  their  physiology,  or 
connected  action  in  the  maintenance  of  the  life  and  growth  of  the 
plant,  have  from  time  to  time  been  explained  or  assumed. 

318.  The  functions  of  nutrition,  which,  in  the  higher  animals, 
comprise  a  variety  of  distinct  processes,  are  reduced  to  the  greatest 

16 


182  THE    FOOD   AND    NUTRITION    OF    PLANTS. 

degree  of  simplicity  in  vegetables.  Imbibition,  assimilation , 
growth,  and  perhaps  secretion,  apparently  include  the  whole. 

819.  Plants  absorb  their  food,  entirely  in  a  liquid  or  gaseous 
form,  by  imbibition,  according  to  the  law  of  endosmosis  (37), 
through  the  walls  of  the  cells  that  form  the  surface,  principally 
those  of  the  newest  roots  and  their  fibrils  (120).  The  fluid  ab- 
sorbed by  the  roots,  mingled  in  the  cells  with  some  previously  as- 
similated matter  they  contain  in  solution  (27,  79),  is  diffused  by 
exosmosis  and  endosmosis  from  cell  to  cell,  aided  by  the  capillary 
action  of  the  fibro-vascular  tissue  of  the  wood,  through  the  newer 
parts  of  which  the  sap  principally  rises  in  stems  of  some  age  (210, 
217) ;  and  is  attracted  into  the  leaves  (or  to  other  parts  of  the  sur- 
face of  the  plant  exposed  to  the  air  and  light)  by  the  exhalation 
which  takes  place  from  them  (314),  and  the  consequent  inspissa- 
tion  of  the  sap.  Here,  exposed  to  the  light  of  the  sun,  the  crude 
sap  is  assimilated,  or  converted  into  organizable  matter  (79),  with 
the  evolution  of  oxygen  gas  into  the  air  ;  and,  thus  prepared  to  form 
vegetable  tissue  or  any  organic  product,  the  elaborated  fluid  is  at- 
tracted into  growing  parts  by  endosmosis,  in  consequence  of  its  con- 
sumption and  condensation  there,  or  is  diffused  through  the  newer 
tissues.  The  fluids  are  transferred  from  place  to  place  by  permea- 
tion and  diffusion,  according  to  a  simple  physical  law.  There  is 
no  movement  in  plants  of  the  nature  of  the  circulation  in  animals 
(37).  Even  in  the  so-called  vessels  of  the  latex  there  is  merely  a 
mechanical  flow  from  the  turgid  tubes  towards  the  place  where  the 
liquid  is  escaping  when  wounded,  or  from  a  part  placed  under  in- 
creased pressure  (63).  The  only  circulation,  or  directly  vital 
movement  of  fluid,  in  vegetable  tissue,  is  that  of  rotation,  or  the  sys- 
tem of  currents  in  or  next  the  layer  of  protoplasm  in  young  and 
active  cells  (36) :  this  movement  is  confined  to  the  individual  cell, 
and  can  have  no  influence  in  the  transference  of  the  sap  from  cell 
to  cell.  Respiration  is  likewise  a  function  of  animals  alone. 
What  is  so  called  in  vegetables  is  connected  with  assimilation, 
and  is  of  entirely  different  physiological  significance,  as  will  pres- 
ently be  shown.  None  of  the  secretions  of  plants  appear,  like 
many  of  those  of  animals,  to  play  any  part,  at  least  any  essential 
part,  in  nutrition.  Many,  if  not  all  of  them,  are  purely  chemical 
transformations  of  the  general  assimilated  products  of  plants,  — 
are  excretions  rather  than  secretions  (80). 

320.  The  appropriation  of  assimilated  matter  in  vegetable  growth. 


THEIR    ELEMENTARY    CONSTITUENTS.  183 

and  the  production  and  multiplication  of  cells,  which  make  up  the 
fabric  of  the  plant,  have  already  been  treated  of  (25-39).  We 
have  now  only  to  consider  what  the  food  of  plants  is,  whence  it  is 
derived,  and  how  it  is  elaborated. 

Sect.  II.     The   Food  and   the    Elementary  Composition  of 

Plants. 

321.  The  Food  and  the  elementary  composition  of  plants  stand 
in  a  necessary  relation  to  each  other.  Since  it  is  not  to  be  sup- 
posed that  plants  possess  the  powerof  creating  any  simple  element, 
whatever  they  consist  of  must  have  been  derived  from  without. 
Their  composition  indicates  their  food,  and  vice  versa.  If  we  have 
learned  the  chemical  composition  of  a  vegetable,  and  also  what  it 
gives  back  to  the  soil  and  the  air,  we  know  consequently  what  it 
must  have  derived  from  without,  that  is,  its  food.  Or,  if  we  have 
ascertained  what  the  plant  takes  from  the  soil  and  air,  and  what  it 
returns  to  them,  we  have  learned  its  chemical  composition,  namely, 
the  difference  between  these  two.  And  when  we  compare  the  na- 
ture and  condition  of  the  materials  which  the  plant  takes  from  the 
soil  and  the  air  with  what  it  gives  back  to  them,  we  may  form  a 
correct  notion  of  the  influence  of  vegetation  upon  the  mineral  king- 
dom. By  considering  the  materials  of  which  plants  are  composed, 
we  may  learn  what  their  food  must  necessarily  contain. 

322,  The  Constituents  of  Plants  are  of  two  kinds  ;  the  earthy  or  in- 
organic, and  the  organic.  It  has  been  stated  (40,  91)  that  various 
earthy  matters,  dissolved  by  the  water  which  the  roots  absorb,  are 
drawn  into  the  plant,  and  at  length  deposited  in  the  wood,  leaves, 
&c.  These  form  the  ashes  which  are  left  on  burning  a  leaf  or  a 
piece  of  wood.  Although  these  mineral  matters  are  often  turned 
to  account  by  the  plant,  and  some  of  them  are  necessary  in  the 
formation  of  certain  products,  (as  the  silex  which  gives  needful 
firmness  to  the  stalk  of  Wheat,  and  the  phosphates  which  are 
found  in  the  grain,)  yet  none  of  them  are  essential  to  simple  vege- 
tation, which  may,  and  sometimes  does,  proceed  without  them. 
These  materials,  the  presence  of  which  is  in  some  sort  accidental, 
though  in  certain  cases  essential,  are  distinguished  as  the  earthy, 
or  mineral,  or  inorganic  constituents  of  plants.  This  class  may 
be  left  entirely  out  of  view  for  the  present.  But  the  analysis  of 
any  newly  formed  vegetable  tissue,  or  of  any  part  of  the  plant, 


184  THE    FOOD    AND    NUTRITION    OF    PLANTS. 

such  as  a  piece  of  wood,  after  the  incrusting  mineral  matter  has 
been  chemically  removed,  invariably  yields  but  three  or  four  ele- 
ments. These,  which  are  indispensable  to  vegetation,  and  make 
up  at  least  from  eighty -eight  to  ninety-nine  7:>er  cent,  of  every  veg- 
etable substance,  are  termed  the  universal,  organic  constituents  of 
plants.  They  are  Carbon,  Hydrogen,  Oxygen,  and  Nitrogen  (10). 
The  proper  vegetable  structure,  that  is,  the  tissue  itself,  uniformly 
consists  of  only  three  of  these  elements,  namely,  carbon,  hydrogen, 
and  oxygen.  These  are  absolutely  essential  and  universal ;  while 
the  fourth,  nitrogen,  is  an  essential  constituent  of  the  protoplasm, 
which  plays  so  important  a  part  in  the  formation  of  the  cells  (27), 
and  of  certain  vegetable  products. 

323.  The  Organic  Constituents.  These  four  elements  must  be  fur- 
nished by  the  food  upon  which  the  vegetable  lives  ;  —  they  must 
be  drawn  from  the  soil  and  the  air;  in  some  cases,  doubtless,  from 
the  latter  source,  as  in  Epiphytes,  or  Air-plants  (132),  but  gener- 
ally and  principally  by  absorption  through  the  roots.  The  plant's 
nourishment  is  wholly  received  either  in  the  gaseous  or  the  liquid 
form;  for  the  leaves  can  imbibe  air  or  vapor  only  (262-268), 
while  the  tissue  of  the  rootlets  is  especially  adapted  to  absorb 
liquids,  and  is  incapable  of  taking  in  solid  matter,  however  mi- 
nutely divided  (Fig.  108-110). 

324.  In  whatever  mode  imbibed,  evidently  the  main  vehicle  of 
the  plant's  nourishment  is  water,  which  as  a  liquid  bathes  its  roots, 
and  in  the  state  of  vapor  continually  surrounds  its  leaves.  We 
have  seen  how  copiously  water  is  taken  up  by  the  growing  plant, 
and  have  formed  some  general  idea  of  its  amount  by  the  quantity 
that  is  exhaled  unconsumed  by  the  leaves  (313).  But  pure  water, 
although  indispensable,  is  insufficient  for  the  nourishment  of  plants. 
It  consists  of  oxygen  and  hydrogen  ;  and  therefore  may  furnish, 
and  doubtless  does  principally  furnish,  these  two  essential  elements 
of  the  vegetable  structure.  But  it  cannot  supply  what  it  does  not 
itself  contain,  namely,  the  carbon  and  nitrogen  which  the  plant 
also  requires. 

325.  Yet  the  question  arises,  whether  the  water  which  the  plant 
actually  imbibes  contains  in  fact  a  quantity  of  these  remaining 
elements.  Though  pure  water  cannot,  may  not  rain-water  supply 
the  needful  carbon  and  nitrogen  ?  It  is  evident  that,  if  the  water 
which  in  such  large  quantities  rises  through  the  plant  and  is  ex- 
haled from  its  leaves  contain  even  a  very  minute  quantity  of  these 


SOURCE    OF    THEIR   ORGANIC    CONSTITUENTS.  185 

ingredients,  in  such  a  form  that  they  may  be  detained  when  the 
superfluous  water  is  exhaled,  this  might  furnish  the  whole  organic 
food  of  the  vegetable  ;  since  the  plant  may  condense  and  accumu- 
late the  carbon  and  nitrogen,  just  as  the  extremely  minute  quantity 
of  earthy  matter  which  the  water  contains  is  in  time  largely  ac- 
cumulated in  the  leaves  and  wood. 

326.  As  respects  the  nitrogen,  nearly  seventy-nine  per  cent,  of 
the  atmosphere  consists  of  this  gas  in  an  uncombined  or  free  state, 
that  is,  merely  mingled  with  oxygen.  And,  being  soluble  to  some 
extent  in  water,  every  rain-drop  that  falls  through  the  air  absorbs 
and  brings  to  the  ground  a  minute  quantity  of  it,  which  is  therefore 
necessarily  introduced  into  the  plant  with  the  water  which  the  roots 
imbibe.  This  accounts  for  the  free  nitrogen  which  is  always  pres- 
ent in  plants. 

327.  The  plant  also  receives,  probably,  a  larger  portion  of  its 
nitrogen  in  the  form  of  ammonia  (or  hartshorn),  a  compound  of 
hydrogen  and  nitrogen,  which  is  always  produced  when  any  ani- 
mal and  almost  any  vegetable  substance  decays,  and  which,  being 
very  volatile,  must  continually  rise  into  the  air  from  these  and 
other  sources.  Besides,  it  appears  to  be  formed  in  the  atmosphere, 
through  electrical  action  in  thunderstorms  (in  the  form  of  nitrate  of 
ammonia).  The  extreme  solubility  of  ammonia  and  all  its  com- 
pounds prevents  its  accumulation  in  the  atmosphere,  from  which  it 
is  greedily  absorbed  by  aqueous  vapor,  and  brought  down  to  the 
ground  by  rain.  That  the  roots  actually  absorb  it  may  be  inferred 
from  the  familiar  facts,  that  plants  grow  most  luxuriantly  when  the 
soil  is  supplied  with  substances  which  yield  much  ammonia,  such 
as  animal  manures ;  and  that  ammonia  may  be  detected  in  the 
juices  of  almost  all  plants.  Rain-water,  therefore,  contains  the 
third  element  of  vegetation,  namely,  nitrogen,  both  in  a  separate 
form  and  in  that  of  ammonia. 

328.  The  source  of  the  remaining  constituent,  carbon,  is  still  to 
be  sought.  Of  this  element  plants  must  require  a  copious  supply, 
since  it  forms  the  largest  portion  of  their  bulk.  If  the  carbon  of  a 
leaf  or  of  a  piece  of  wood  be  obtained  separate  from  the  other  or- 
ganic elements,  —  which  may  be  done  by  charring,  that  is,  by  heat- 
ing it  out  of  contact  with  the  air,  so  as  to  drive  off  the  oxygen,  hy- 
drogen, and  carbon,  —  although  a  small  part  of  the  carbon  is  ne- 
cessarily lost  in  the  operation,  yet  what  remains  perfectly  preserves 
the  shape  and  bulk  of  the  original  body,  even  to  that  of  its  most 

16* 


186  THE    FOOD   AND    NUTRITION    OF    PLANTS. 

delicate  cells  and  vessels.  '  With  the  exception  of  the  ashes,  this 
consists  of  carbon,  or  charcoal,  amounting  to  from  forty  to  sixty 
per  cent,  by  weight,  of  the  original  material.  Carbon  is  itself  a 
solid,  absolutely  insoluble  in  water,  and  therefore  incapable  of  as- 
sumption by  the  plant.  The  chief,  if  not  the  only  fluid  compound 
of  carbon  which  is  naturally  presented  to  the  plant,  is  that  of  car- 
bonic acid  gas,  which  consists  of  carbon  united  with  oxygen.  This 
gas  makes  up  on  the  average  one  two-thousandth  of  the  bulk  of  the 
atmosphere  ;  from  which  it  may  be  directly  absorbed  by  the  leaves. 
But,  being  freely  soluble  in  water  up  to  a  certain  point,  it  must  also 
be  carried  down  by  the  rain  and  imbibed  by  the  roots.  The  car- 
bonic acid  of  the  atmosphere  is  therefore  the  great  source  of  carbon 
for  vegetation. 

329.  It  appears,  then,  that  the  atmosphere  —  considering  water 
in  the  state  of  vapor  to  form  a  component  part  of  it  —  contains  all 
the  essential  materials  for  the  growth  of  vegetables,  and  in  the  form 
best  adapted  to  their  use,  namely,  in  the  fluid  state.  It  furnishes 
water,  which  is  not  only  food  itself,  inasmuch  as  it  supplies  oxygen 
and  hydrogen,  but  is  likewise  the  vehicle  of  the  others,  conveying 
to  the  roots  what  it  has  gathered  from  the  air,  namely,  the  requisite 
supply  of  nitrogen,  either  separately  or  in  the  form  of  ammonia, 
and  of  carbon  in  the  form  of  carbonic  acid. 

330.  These  essential  elements,  the  whole  proper  food  of  plants, 
may  he  absorbed  by  the  leaves  directly  from  the  air,  in  the  state  of 
gas  or  vapor.  Doubtless  most  plants  actually  take  in  a  portion  of 
their  food  in  this  way,  at  least  when  other  supply  is  arrested. 
Drooping  foliage  may  be  revived  by  sprinkling  with  water,  or  by 
placing  them  in  a  moist  atmosphere.  A  vigorous  branch  of  the 
common  Live-for-ever  (Sedum  Telephium),  or  of  many  such 
plants,  it  is  well  known,  will  live  and  grow  for  a  whole  season 
when  pinned  to  a  dry,  bare  wall ;  and  the  Epiphytes,  or  Air-plants 
(132),  as  they  are  aptly  called,  must  derive  their  whole  sustenance 
immediately  from  the  air ;  for  they  have  no  connection  with  the 
ground. 

331.  But  the  peculiar  office  of  leaves  is  something  different  from 
that  of  absorbing  nourishment.  As  a  comprehensive  statement, 
leaving  extraordinary  cases  out  of  view,  it  may  be  said  that  plants, 
although  they  derive  their  food  from  the  air,  receive  it  chiefly 
through  their  roots.  The  aqueous  vapor,  condensed  into  rain  or 
dew,  and  bringing  with  it  to  the  ground  a  portion  of  carbonic  acid. 


SOURCE    OF    THEIR    ORGANIC    CONSTITUENTS.  187 

and  of  nitrogen  or  ammonia^  &c.,  supplies  the  appropriate  food  of 
the  plant  to  the  rootlets.  Imbibed  by  these,  it  is  conveyed  through 
the  stem  and  into  the  leaves,  where  the  now  superfluous  water  is 
restored  to  the  atmosphere  by  exhalation,*  while  the  residue  is  con- 
verted into  the  proper  nourishment  and  substance  of  the  vegetable. 

332.  The  atmosphere  is  therefore  the  great  storehouse  from 
which  vegetables  derive  their  nourishment ;  and  it  might  be  clearly 
shown  that  all  the  constituents  of  plants,  excepting  the  small  earthy 
portion  that  many  can  do  without,  have  at  some  period  formed  a 
part  of  the  atmosphere.  The  vegetable  kingdom  represents  an 
amount  of  matter,  which  the  force  of  organization  has  withdrawn 
from  the  air,  and  confined  for  a  time  to  the  surface. 

333.  Does  it  therefore  follow  that  the  soil  merely  serves  as  a 
foothold  to  plants,  and  that  all  vegetables  obtain  their  whole  nour- 
ishment directly  from  the  atmosphere  ?  This  must  have  been  the 
case  with  the  first  plants  that  grew,  when  no  vegetable  or  animal 
matter  existed  in  the  soil ;  and  no  less  so  with  the  first  vegetation 
that  covers  small  volcanic  islands  raised  in  our  own  times  from  the 
sea,  or  the  surface  of  lava  thrown  from  ordinary  volcanoes.  No 
vegetable  matter  is  brought  to  these  perfectly  sterile  mineral  soils, 
except  the  minute  portion  contained  in  the  seeds  wafted  thither  by 
winds  or  waves.  And  yet  in  time  a  vast  quantity  is  produced, 
which  is  represented  not  only  by  the  existing  vegetation,  but  by 
the  mould  that  the  decay  of  previous  generations  has  imparted  to 
the  soil.  We  arrive  at  the  same  result  by  the  simple  experiment 
of  causing  a  seed  of  known  weight  to  germinate  on  powdered 
flints,  watered  by  rain-water  alone.     When  the  young  plant  has 


*  The  water  exhaled  may  be  again  absorbed  by  the  roots,  laden  with  a  new 
supply  of  the  other  elements  from  the  air,  again  exhaled,  and  so  on;  as  is 
beautifully  illustrated  by  the  cultivation  of  plants  in  closed  Ward  cases,  where 
plants  are  seen  to  flourish  for  a  long  time  with  a  very  limited  supply  of  water, 
every  particle  of  which  (except  the  small  portion  actually  consumed  by  the 
plants)  must  pass  repeatedly  through  this  circulation.  This  vegetable  micro- 
cosm well  exhibits  the  actual  relations  of  water,  «S6c.,  to  vegetation  on  a  large 
scale  in  nature ;  where  the  water  is  alternately  and  repeatedly  raised  by 
evaporation  and  recondensed  to  such  extent  that  what  actually  falls  in  rain  is 
estimated  to  be  reevaporated  and  rained  down  (on  an  average  throughout  the 
world)  ten  or  fifteen  times  in  the  course  of  a  year.  In  this  way  the  atmos- 
phere is  repeatedly  washed  by  the  rain;  and  those  vapors  washed  out  which 
else  by  their  accumulation  would  prove  injurious  to  men  and  animals,  and 
conveyed  to  the  roots  of  plants,  which  they  are  especially  adapted  to  nourish. 


188  THE    FOOD    AND    NUTRITION    OF    PLANTS. 

attained  the  fullest  development  of  which  it  is  capable  under  these 
circumstances,  it  will  be  found  to  weigh  (after  due  allowance  for 
the  silex  it  may  have  taken  up)  perhaps  fifty  or  one  hundred  times 
as  much  as  the  original  seed.  There  can  be  no  question  as  to  the 
source  of  this  vegetable  matter  in  all  these  6ases.  The  requisite  mU' 
terials  exist  in  the  air.  Plants  possess  the  peculiar  faculty  of  draw- 
ing them  from  the  air.  The  air  must  have  furnished  the  whole. 
This  conclusion  is  amply  confirmed  by  a  great  variety  of  familiar 
facts ;  such  as  the  accumulation  of  vegetable  matter  in  peat-bogs, 
and  of  mould  in  neglected  fields,  in  old  forests,  and  generally 
wherever  vegetation  is  undisturbed.  Since  this  rich  mould,  instead 
of  diminishing,  regularly  increases  with  the  age  of  the  forest  and 
the  luxuriance  of  vegetation,  the  trees  must  have  drawn  from  the 
air,  not  only  the  vast  amount  of  carbon,  &c.,  that  is  stored  up  in 
their  trunks,  but  an  additional  quantity  which  is  imparted  to  the 
soil  in  the  annual  fall  of  leaves,  &c. 

334.  Still  it  by  no  means  follows,  that  each  plant  draws  all  its 
nourishment  directly  from  the  air.  This  unquestionably  happens 
in  some  of  the  special  cases  just  mentioned  ;  with  Air- plants,  and 
with  those  that  first  vegetate  on  volcanic  earth,  bare  rocks,  naked 
walls,  or  pure  sand.  But  it  is  particularly  to  be  remarked,  that 
only  certain  tribes  of  plants  will  continue  to  live  under  such  cir- 
cumstances, and  that  none  of  the  vegetables  most  useful  as  food 
for  man  or  the  higher  animals  will  thus  thrive  and  come  to  matu- 
rity. In  nature,  the  races  of  plants  that  will  grow  at  the  entire 
expense  of  the  air,  such  as  Lichens,  Mosses,  Ferns,  and  certain 
succulent  tribes  of  Flowering  plants,  gradually  form  a  soil  of  veg- 
etable mould  during  their  life,  which  they  increase  in  their  decay ; 
and  the  successive  generations  live  more  vigorously  upon  the  in- 
heritance, being  supported  partly  upon  what  they  draw  from  the 
air,  and  partly  upon  the  ancestral  accumulation  of  vegetable 
mould.  Thus,  each  generation  may  enrich  the  soil,  even  of  those 
plants  that  draw  largely  upon  vegetable  matter  thus  accumulated ; 
for  it  annually  restores  a  portion  by  its  dead  leaves,  &c.,  and  when 
it  dies  it  bequeathes  to  the  soil,  not  only  all  that  it  took  from  it,  but 
all  that  it  drew  from  the  air.  It  is  in  this  way  that  the  lower  tribes 
and  so-called  useless  plants  create  a  soil,  which  will  in  time  sup- 
port the  higher  plants  of  immediate  importance  to  man  and  the 
higher  animals,  but  which  could  never  grow  and  perfect  their 
fruit,  if  left,  like  their  humble  but  indispensable  predecessors,  to 


THEIR    EARTHY    CONSTITUENTS.  189 

derive  an  unaided  subsistence  directly  from  the  inorganic  world. 
While  it  is  strictly  true,  therefore,  that  all  the  organic  elements 
have  been  originally  derived  from  the  air,  it  is  not  true  that  M'hat 
is  contained  in  almost  any  given  plant,  or  in  any  one  crop,  is  im- 
mediately drawn  from  this  source.  A  part  of  it  is  thus  supplied, 
but  in  proportions  varying  greatly  in  different  species  and  under 
different  circumstances.  Undisturbed  vegetation  consequently 
tends  always  to  enrich  the  soil.  But  in  agriculture  the  crop  is 
ordinarily  removed  from  the  land,  and  with  it  not  only  what  it  has 
taken  from  the  earth,  but  also  what  it  has  drawn  from  the  air  ; 
and  the  soil  is  accordingly  impoverished.  Hence  the  farmer  finds 
it  necessary  to  follow  the  example  of  nature,  and  to  restore  to  the 
land,  in  the  form  of  manure,  an  amount  substantially  equivalent  to 
what  he  takes  away. 

335.  The  mode  in  which  vegetable  mould  is  turned  to  account 
by  growing  plants  has  not  yet  been  sufficiently  investigated.  Ac- 
cording to  Liebig,  the  decaying  vegetable  matter  is  not  employed 
until  it  has  been  resolved  into  its  original  inorganic  elements, 
namely,  into  water,  carbonic  acid,  ammonia,  &c.  ;  which,  slowly 
absorbed  by  the  water  that  percolates  the  soil,  are  imbibed  by  the 
roots.  Others  suppose  that  a  portion  of  the  food  which  plants  de- 
rive from  decaying  vegetable  matter  may  consist  of  soluble,  still 
organic  compounds.  The  economy  of  the  greenless  parasitic 
plants  (135)  is  adduced  in  confirmation  of  this  view  ;  but  these  are 
nourished  by  the  foster  plant  just  as  its  own  flowers  are  nourished. 
Decisive  evidence  to  the  point  is  furnished  by  Fungi,  the  greater 
part  of  which  live  upon  decaying  organic  matter,  and  have  not  the 
power  of  forming  organizable  products  from  inorganic  materials ; 
and  there  is  reason  to  think,  that  at  least  one  Phsenogamous  plant 
(our  Monotropa,  137)  lives  in  much  the  same  way. 

336.  The  Earthy  Constituents.  The  mineral  substances  which  form 
the  inorganic-  constituents  of  plants  (322)  are  furnished  by  the  soil, 
and  are  primarily  derived  from  the  slow  disintegration  and  decom- 
position of  the  rocks  and  earths  that  compose  it.*  These  are  dis- 
solved, for  the  most  part,  in  very  minute  proportions,  in  the  water 
which  percolates  the  soil  (aided,  as  to  the  more  insoluble  earthy 
salts,  by  the  carbonic  acid  which  this  water  contains),  and  with  this 


*  According  to  Liebig,  the  quantity  of  potash  contained  in  a  layer  of  soil 
formed  by  the  disintegration  of  40,000  square  feet  of  the  following  rocks,  &c.. 


190 


THE    FOOD    AND    NUTRITION    OF    PLANTS. 


water  are  taken  up  by  the  roots.  However  minute  their  proportion 
in  the  water  which  the  roots  imbibe,  the  plant  concentrates  and 
accumulates  them,  as  it  does  its  most  dilute  inorganic  food,  by  the 
constant  exhalation  of  the  water  from  the  leaves,  until  they  amount 
to  an  appreciable  quantity,  often  to  a  pretty  large  percentage,  of  the 
solid  matter  of  the  vegetable.  As  might  be  expected  (311),  the 
leaves  contain  a  much  larger  amount  of  ashes,  or  earthy  matter, 
than  the  wood,  but  the  trunk  more  than  the  branches  (210).  Her- 
baceous plants  also  accumulate  more  than  trees  in  proportion  to 
their  weight  when  dry.* 

337.  The  ashes  left  after  combustion  are  mo.stly  composed  of 
the  "  alkaline  chlorides,  with  the  bases  of  potash  and  soda,  earthy 
and  metallic  phosphates,  caustic  or  carbonate  of  lime  and  magne- 
sia, silica,  and  oxides  of  iron  and  of  manganese.  Several  other 
substances  are  also  met  with  there,  but  in  quantities  so  small  that 
they  may  be  neglected."  Different  species  growing  in  the  same 
soil  appear  to  take  in  some  portion  of  all  such  materials  that  are 


to  the  depth  of  twenty  inches,  is  as  follows.     This  quantity  of  Feldspar  (a 


.      1,152,000  lbs. 

from  200,000  to  400,000    " 

"      47,500    "     75,000    " 

"     100,000    "  200,000    « 

"       87,000    "   300,000    « 


large  component  of  granite,  &c.)  contains 
Clinkstone,  .... 

Basalt,    ..... 
Clay-slate,  ..... 
Loam^    ..... 

The  silex  yielded  to  the  soil  by  the  gradual  decomposition  of  granite  and 
other  rocks  is  in  the  form  of  a  silicate  of  potash  or  other  alkali,  which,  though 
insoluble  in  pure  water,  is  slowly  acted  upon  and  dissolved  by  the  united  ac- 
tion of  water  and  carbonic  acid,  or  more  largely  by  water  impregnated  with 
carbonate  of  potash,  which  is  abundantly  liberated  during  the  natural  decom- 
position of  these  rocks. 

*  The  subjoined  results,  selected  from  Boussingault,  exhibit  in  a  tabular 
form  the  relative  quantities  of  organic  and  inorganic  constituents  in  several 
kinds  of  herbage,  compared,  in  several  cases,  with  the  root  or  grain.  The 
water  was  previously  driven  off  by  desiccation. 


k 

^ 

is, 

V.   3 

f 

6 

s 

1 

1 

i 

i 

1 

JS 

Carbon, 

^ 

t§ 

^ 

^ 

(^ 

^ 

O 

48.48 

^ 

38.10:  42.75 

44.80 

43.72 

45.80 

46.06 

47.53 

46.10 

Hydrogen, 

Oxygen, 

Nitrogen, 

5.10|     5.77 

5.10 

6.00 

5.00 

6.09 

4.69 

5.41 

5.80 

30.801  43.58 

30.50 

44.88 

35.57 

40.53 

37.96 

38.79 

43.40 

4  501     1.66 

2.30 

1.50 

2.31 

4.18 

2.06 

0.35 

2.27 

Ashes, 

21.50^     6.24 

17.301 

3.90 

1132 

3.14 

776 

6.97 

2.43 

100.00 

100.00  lOO.OU 

100.00  lOO.OOf  100  00  100.00 

100  00  100.00 

THEIR  EARTHY  CONSTITUENTS.  191 

naturally  presented  to  them  in  solution,  but  not,  however,  in  the 
same  proportions,  nor  in  any  close  proportion  to  the  relative  solu- 
bility of  these  several  substances :  while,  on  the  other  hand,  the 
same  species  in  different  localities,  under  generally  similar  cir- 
cumstances, and  also  each  of  its  particular  parts  or  organs,  con- 
tains, or  tends  to  contain,  the  same  mineral  constituents  in  nearly 
the  same  proportion.  One  base,  however,  is  often  substituted  for 
another,  equivalent  for  equivalent,  as  magnesia  for  lime,  soda  for 
potash.  The  roots,  therefore,  appear  to  have  a  certain  power  of 
selection  in  respect  to  these  mineral  materials.  Nor  is  it  a  valid 
objection  to  this  view,  that  they  absorb  poisons  which  destroy  them. 
These  are  either  organic  products,  such  as  opium ;  or  else  are 
corrosive  substances,  such  as  sulphate  of  copper,  which  disorgan- 
ize the  rootlets,  and  are  then  indiscriminately  imbibed  by  mere 
capillary  attraction.  For  mutilated  roots  or  stems  absorb  all  dis- 
solved materials  of  the  proper  density  that  are  presented  to  them, 
not  only  in  much  larger  quantity  (so  long  as  the  cut  is  fresh) 
than  do  the  uninjured  rootlets,  but  almost  indifferently,  and  in  the 
same  proportion  that  they  absorb  the  water  they  are  dissolved  in. 

338.  In  the  ashes,  only  the  salts  which  resist  the  action  of  heat, 
such  as  the  phosphates,  sulphates,  and  hydrochlorates,  are  in  the 
state  in  which  they  existed  in  the  plant  itself.  A  great  part  of  the 
bases  were  combined  whh  organic  acids,  formed  in  the  plant,  and 
most  largely  with  the  oxalic  (90,  91)  :  these  compounds  are  by 
incineration,  or  by  subsequent  exposure  to  the  air,  principally  con- 
verted into  carbonates. 

339.  It  being  indispensable  that  a  plant  should  find  in  the  soil 
such  mineral  matters  as  are  necessary  to  its  growth  or  perfect  de- 
velopment, we  are  enabled  to  understand  why  various  species  will 
only  flourish  in  particular  soils  or  situations ;  why  plants  which 
take  up  common  salt,  &c.,  are  restricted  to  the  sea-shore  and 
to  the  vicinity  of  salt-springs  ;  why  numerous  weeds  which  grow 
chiefly  around  dwellings,  and  follow  the  footsteps  of  man  and  the 
domestic  animals,  flourish  only  in  a  soil  abounding  in  nitrates 
(their  ashes  containing  a  notable  quantity  either  of  nitrate  of  pot- 
ash or  of  lime) ;  why  the  Vine  requires  alkaline  manures,  to  re- 
place the  large  amount  of  tartrate  of  potash  which  the  grapes  con- 
tain ;  and  why  Pines  and  Firs,  the  ashes  of  which  contain  very 
little  alkali,  will  thrive  in  the  thinnest  and  most  sterile  soil,  while 
the  Beech,  Maple,  Elm,  &c.,  abounding  with  potash,  are  only  ' 
found  in  strong  and  fertile  land. 


192  THE    FOOD    AND    NUTRITION    OF    PLANTS. 

340.  Where  vegetation  is  undisturbed  by  man,  all  these  needful 
earthy  materials,  which  are  drawn  from  the  soil  during  the  growth 
of  the  herbage  or  forest,  are  in  time  restored  to  it  by  its  decay, 
in  an  equally  soluble  form,  along  with  organic  matter  which  the 
vegetation  has  formed  from  the  air.  But  in  cultivation,  the  prod- 
uce is  carried  away,  and  with  it  the  materials  which  have  been 
slowly  yielded  by  the  soil.  "  A  medium  crop  of  Wheat  takes 
from  one  acre  of  ground  about  12  pounds,  a  crop  of  Beans  about 
20  pounds,  and  a  crop  of  Beets  about  1 1  pounds,  of  phosphoric 
acid,  besides  a  very  large  quantity  of  potash  and  soda.  It  is  obvi- 
ous that  such  a  process  tends  continually  to  exhaust  arable  land  of 
the  mineral  substances  useful  to  vegetation  which  it  contains,  and 
that  a  time  must  come  when,  without  supplies  of  such  mineral 
matters,  the  land  would  become  unproductive  from  their  abstrac- 
tion  In  the  neighbourhood  of  large  and  populous  towns,  for 

instance,  where  the  interest  of  the  farmer  and  market-gardener  is  to 
send  the  largest  possible  quantity  of  produce  to  market,  consuming 
the  least  possible  quantity  on  the  spot,  the  want  of  saline  principles 
in  the  soil  would  very  soon  be  felt,  were  it  not  that  for  every  wag- 
on-load of  greens  and  carrots,  fruit  and  potatoes,  corn  and  straw, 
that  finds  its  way  into  the  city,  a  wagon-load  of  dung,  containing 
each  and  every  one  of  these  principles  locked  up  in  the  several 
crops,  is  returned  to  the  land,  and  proves  enough,  and  often  more 
than  enough,  to  replace  all  that  has  been  carried  away  from  it."  * 
The  loss  must  either  be  made  up  by  such  equivalent  return,  or  the 
land  must  lie  fallow  from  time  to  time  until  these  soluble  substan- 
ces are  restored  by  further  disintegration  of  the  materials  of  the 
soil :  or  meanwhile  the  more  exhausting  crops  may  be  alternated 
with  those  that  take  least  from  the  soil  and  most  from  the  air ;  or 


*  Boussingault, -Eco7iomie  J?«m/e;  from  the  Engl.  Trans.,  p.  493.  Further: 
—  "  It  may  be  inferred  that,  in  the  most  frequent  case,  namely,  that  of  arable 
lands  not  sufficiently  rich  to  do  without  manure,  there  can  be  no  continuous 
[independent]  cultivation  without  annexation  of  meadow;  in  other  words, 
one  part  of  the  farm  must  yield  crops  without  consuming  manure,  so  that  this 
may  replace  the  alkaline  and  earthy  salts  which  are  constantly  withdrawn  by 
successive  harvests  from  another  part.  Lands  enriched  by  rivers  alone  permit 
of  a  total  and  continued  export  of  their  produce  without  exhaustion.  Such 
are  the  fields  fertilized  by  the  inundations  of  the  Nile;  and  it  is  difficult  to 
form  an  idea  of  the  prodigious  quantities  of  phosphoric  acid,  magnesia,  and 
potash,  which,  in  a  succession  of  ages,  have  passed  out  of  Egypt  with  her  in- 
cessant exports  of  corn."  —  p.  503. 


THEIR    EARTHY    CONSTITUENTS. 


193 


with  one  which,  like  clover,  although  it  takes  up  77  pounds  of  al- 
kali per  acre,  may  be  consumed  on  the  field,  so  as  to  restore  most 
of  this  alkali  in  the  manure  for  the  succeeding  crop. 

341.  It  has  been  asserted  that  the  advantage  of  preceding  a 
wheat  crop  by  one  of  leguminous  plants  (such  as  Peas,  Clover, 
Lucerne,  &c.),  or  of  roots  or  tubers,  is  owing  to  the  fact  that  these 
leave  the  phosphates,  &c.  nearly  untouched  for  the  wheat  which  is 
to  follow,  and  which  largely  abstracts  them.  The  results  of  Bous- 
singault's  experiments  and  analyses  show  that  these  products  are 
far  from  having  the  deficiency  of  phosphates  which  was  alleged. 
"  For  example,  beans  and  haricots  take  20  and  13.7  pounds  of 
phosphoric  acid  from  every  acre  of  land ;  potatoes  and  beet-root 
take  11  and  12.8  pounds  of  that  acid,  exactly  what  is  found  in  a 
crop  of  wheat.  Trefoil  is  equally  rich  in  phosphates  with  the 
sheaves  of  corn  that  have  gone  before  it."  *  His  further  re- 
searches seem  to  show  that  these  crops  exhaust  the  soil  less  than 
the  cereal  grains,  in  part  at  least,  on  account  of  the  large  quantity 
of  organic  matter,  rich  in  nitrogen,  which  they  leave  to  be  incor- 
porated with  the  soil.  The  theory  of  rotation  in  crops,  founded  by 
De  Candolle  on  the  assumption  that  excretions  from  the  roots  of  a 
plant  accumulated  in  the  soil  until  in  time  they  became  injurious 
to  that  crop,  but  furnished  appropriate  food  for  a  different  species, 
is  entirely  abandoned  as  an  explanation ;  and  even  the  fact  that 


*  Boussingault,  I.  c,  p.  497.  —  Subjoined  is  a  table,  from  the  same  work,  of 
the  percentage  of  Mineral  Substances  taken  up  from  the  soil  by  various  plants 
grown  at  Bechelbronn. 


Acids 

J. 

.2  0} 

6 

u 

is 

Substances  which 

.o 

■i 

o 

<D 

.2 

s_  ei 

'^■'g 

yielded  the  Ashes. 

1 

•a 
1 

Cl, 

1 

.CL, 

o 

1 
5 

1 

1 
1 

d 

r5 

35 

o  a 
II 

8  ^ 

6^ 

Potatoes, 

13.4 

7.1 

lis 

2.7 

1.8 

~54 

51  5  [traces 

5.6 

05 

~0T 

Mangel-Wurzeb 

16.1 

1.6 

6.1 

5.2 

7.0 

4  4 

39.0 

60 

8.0 

25 

4.2 

Turnips, 

14.0 

10.9 

6.0 

2.9 

10.9 

4.3 

33.7 

4.1 

64 

12 

5.5 

Potato-tops, 

11.0 

22 

10.8 

16 

2.3 

1.8 

44.5  traces 

13.0 

5.2 

7.6 

Wheat, 

0.0 

1.0 

47.0 

traces 

2.9 

15.9 

29.5  traces 

1.3 

0.0 

24 

Wheat-straw, 

0.0 

1.0 

3.1 

0.6 

8.5 

5.0 

9.2 

0.3 

67.6 

1  0 

3.7 

Oats, 

1.7 

1.0 

14.9 

0.5 

3.7 

7.7 

12.9 

00 

53.3 

1.3 

3.0 

Oat-straw, 

3.2 

4.1 

3.0 

4.7 

8.3 

2.8 

24.5 

4.4 

40.0 

2.1 

2.9 

Clover, 

25.0 

25 

6.3 

2.6 

24  6 

6.3 

266 

0.5 

5.3 

0.3 

0.0 

Peas,     . 

0.5 

4.7 

30.1 

1.1 

10.111.9 

35.3 

2.5 

1,5 

traces 

23 

French  beans, 

3.3 

1.3 

26.8 

0.1 

5.811.5 

49.1 

0.0 

1.0 

traces 

1.1 

Horse  beans, 

1.0 

1.6 

34.2 

0.7 

5  1    8.6 

45  2 

0.0 

0.5 

traces 

3.1 

17 


194  THE  FOOD  AND  NUTRITION  OF  PLANTS. 

such  excretions  are  formed,  at  least  to  any  considerable  extent,  is 
not  made  out.  That  they  could  accumulate  and  remain  in  the  soil 
without  undergoing  decomposition  is  apparently  impossible. 

Sect.  III.     Assimilation,   oh  Vegetable   Digestion,  and   its 

Results. 

342.  We  have  reached  the  conclusion,  that  the  universal  food  of 
plants  is  rain-water,  which  has  absorbed  some  carbonic  acid  gas 
and  nitrogen  (partly  in  the  form  of  ammonia  or  of  other  com- 
pounds) from  the  air,  or  dissolved  them  from  the  remains  of  for- 
mer vegetation  in  the  soil,  whence  it  has  also  taken  up  a  variable 
(yet  more  or  less  essential)  quantity  of  earthy  matter. 

343.  This  fluid,  imbibed  by  the  roots,  and  carried  upwards 
through  the  stem,  receives  the  name  of  sap,  or  crude  sap  (79). 
Daring  its  ascent,  its  properties  are  often  more  or  less  altered, 
chiefly  by  dissolving  the  soluble  organized  matter  it  meets  with ; 
thus  becoming  sweet  in  the  Maple,  &c.,  and  acquiring  different 
sensible  properties  in  diflTe rent  species.  This  dissolved -portion  is 
already  elaborated  food,  and  may  therefore  be  immediately  em- 
ployed in  vegetable  growth.  But  the  crude  sap  itself  is  merely 
raw  material,  unorganized,  mineral  matter,  as  yet  incapable  of 
forming  a  part  of  the  living  structure.  Its  conversion  into  organ- 
ized matter  constitutes  the  process  of 

344.  Assimilation  (12,  15),  or  what,  from  an  analogy  with  an 
animal  function,  is  usually  termed  Vegetable  Digestion.  To  un- 
dergo this  important  change,  the  crude  sap  is  attracted  into  the 
leaves,  or  other  green  parts  of  the  plant,  which  constitute  the  ap- 
paratus of  vegetable  digestion,  where  it  is  exposed  to  the  light  of 
the  sun,  under  which  influence  alone  can  this  change  be  effected. 
Under  the  influence  of  solar  light,  the  fabric  is  itself  constructed, 
and  the  chlorophyll,  or  green  matter  of  plants,  upon  which,  or 
in  connection  with  which,  the  light  exerts  its  wonderful  action,  is 
first  developed.  When  plants  are  made  to  grow  in  insufficient 
light,  as  when  potatoes  throw  out  shoots  in  cellars,  this  green 
matter  is  not  formed.  When  light  is  withdrawn,  it  is  soon  decom- 
posed ;  as  we  see  when  Celery  is  blanched  by  heaping  the  soil 
around  its  stems.  So,  also,  the  naturally  greenless  leaves  of  plants 
parasitic  upon  the  roots  or  stems  of  other  species  (135)  have  no 
direct  power  of  assimilation,  but  feed  upon  and  grow  at  the  ex- 


ASSIMILATION.  195 

pense  of  already  assimilated  matter.  But  all  green  parts  of  plants, 
such  as  the  cellular  outer  bark  of  most  herbs,  act  upon  the  sap  in 
the  same  manner  as  leaves,  even  supplying  their  place  in  plants 
which  produce  few  or  no  leaves,  as  in  the  Cactus,  &c.  Under  the 
mfluence  of  light,  an  essential  preliminary  step  in  vegetable  diges- 
tion is  accomplished,  namely,  the  concentration  of  the  crude  sap 
by  the  evaporation  or  exhalation  of  the  now  superfluous  water,  the 
mechanism  and  various  consequences  of  which  have  already  been 
considered  (267,  313). 

345.  We  have  only  to  consider  the  further  agency  of  light  in 
the  process  of  vegetable  digestion  itself,  namely,  its  action  in  the 
leaf  upon  the  concentrated  sap.  Here  it  accomplishes  two  per- 
fectly unparalleled  results,  which  essentially  characterize  vegeta- 
tion, and  upon  which  all  organized  existence  absolutely  depends 
(1,  18).  These  are, —  1st.  The  chemical  decomposition  of  one  or 
more  of  the  substances  in  the  sap  which  contain  oxygen  gas,  and 
the  liberation  of  this  oxygen  at  the  ordinary  temperature  of  the 
air.  The  chemist  can  in  certain  cases  liberate  oxygen  gas  from 
its  compounds,  but  only  with  the  aid  of  powerful  reagents,  or  of  a 
heat  equal  to  that  of  red-hot  iron.  2d.  The  transformation  of  this 
mineral  food,  this  inorganic  into  organic  matter,  —  the  organized 
substance  of  living  plants,  and  consequently  of  animals.  These 
two  operations,  although  separately  stated  to  convey  a  clearer  idea 
of  the  results,  are  in  fact  but  different  aspects  of  one  great  process. 
We  contemplate  the  first,  when  we  consider  what  the  plant  gives 
back  to  the  air  ;  —  the  second,  when  we  inquire  what  it  retains  as 
the  materials  of  its  own  growth.  The  concentrated  sap  is  decom- 
posed ;  the  portion  which  is  not  required  in  the  growth  of  the  plant 
is  returned  to  the  air ;  and  the  remaining  elements  are  at  the  same 
time  rearranged,  so  as  to  form  peculiar  organic  products. 

346.  The  principal  material  given  back  to  the  air,  in  this  pro- 
cess, is  oxygen  gas,*  that  element  of  our  atmosphere  which  alone 


*  A  small  proportion  of  nitrogen  gas  is  likewise  almost  constantly  exhaled 
from  the  leaves;  but  this  appears  to  come  from  the  nitrogen  which  the  water 
imbibed  by  the  roots  had  absorbed  from  the  air  (326),  and  which  passes  off 
unaltered  from  the  leaves  when  this  water  is  evaporated,  or  from  the  air  which 
the  rootlets  directly  absorb  to  some  extent.  In  the  course  of  vegetation,  no 
more  nitrogen  is  given  out  than  what  is  thus  taken  in,  and  probably  not  so 
much.  So  that  the  exhalation  of  nitrogen  may  be  lefl  out  of  the  general  view 
of  the  changes  which  are  brought  about  in  vegetation. 


196  THE    FOOD    AND    NUTRITION    OF    PLANTS. 

renders  it  fit  for  the  breathing  and  life  of  animals.  That  the  foli- 
age of  plants  in  sunshine  is  continually  yielding  oxygen  gas  to  the 
surrounding  air  has  been  familiarly  known  since  the  daysof  Ingen- 
houss  and  Priestley,  and  may  at  any  moment  be  verified  by  sim- 
ple experiments.  The  readiest  way  is,  to  expose  a  few  freshly 
gathered  leaves  to  the  sunshine  in  a  glass  vessel  filled  with  water, 
and  to  collect  the  air-bubbles  which  presently  arise  while  the  light 
falls  upon  them,  but  which  cease  to  appear  when  placed  in  shad- 
ow. This  air,  when  examined,  proves  to  be  free  oxygen  gas.  In 
nature,  diffused  daylight  produces  this  result ;  but  in  our  rude  ex- 
periments, direct  sunshine  is  generally  necessary.  What  is  the 
source  of  this  oxygen  gas,  which  is  given  up  to  the  air  just  in  pro- 
portion to  the  vigor  of  assimilation  in  the  leafy  plant,  or,  in  other 
words,  to  the  consumption  of  crude  sap  ? 

347.  To  take  for  illustration  the  case  which  exhibits  the  general 
result  (and  whether  this  is  actually  attained   at  one  operation,  or 
not,  does  not  affect  the  view),  and  enables  us  directly  to  contrast 
the  materials  with  the  \innc\pa\  product  of  vegetation,  we  will  sup- 
pose the  plant  is  assimilating  its  food  immediately  into  Cellulose,  or 
the  substance  of  which  its  tissue  consists  (27).     This  matter,  when 
in  a  pure  state,  and   free  from  incrusting  materials,  has  a  per- 
fectly uniform  composition  in  all  plants.    It  is  composed  of  carbon, 
hydrogen,  and  oxygen,  of  which   the  latter  two  exist  in  the  same 
proportions  as  in  water.*     It  may  therefore  be  said  to  consist  of 
carbon  and  the  elements  of  water.     These  materials  are  necessa- 
rily furnished  by  the  plant's  food.     But  the  universal  food  of  the 
plant,  that  which  is  only  and  absolutely  essential  to  bare  vegeta 
tion   (324,  329),  is  carbonic  acid  and  water.     If  this  be  decom 
posed  in  vegetation,  and  the   carbonic  acid   give  up  its  oxygen 
there  remain  carbon  and  water,  or  rather  the  elements  of  water 
—  the  very  composition  of  cellulose  or  vegetable  tissue.     Doubt 
less,  then,  the  oxygen  which  is  rendered  to  the  air  in  vegetation 
comes  from  the  carbonic  acid  which,  as  we  have  seen  (328),  the 
plant  took  from  the  air. 

348.  This  view  may  be  confirmed  by  direct  experiment.  We 
have  seen  that  many  plants  must,  and  all  may,  imbibe  the  whole  or 
a  part  of  their  food  directly  from  the  air  into  their  leaves  (132, 

*  Cellulose  is  chemically  composed  of  12  equivalents  of  Carbon,  10  of  Hy- 
drogen, and  10  of  Oxygen,  viz.  C»2,  U"^,  O^o. 


ASSIMILATION.  197 

330).  All  leafy  plants  doubtless  obtain  a  part  of  their  carbonic 
acid  in  this  way.  It  is  accordingly  found,  that  when  a  current  of 
carbonic  acid  is  made  slowly  to  traverse  a  glass  globe  containing 
a  leafy  plant  exposed  to  the  full  sunshine,  the  carbonic  acid  disap- 
pears, and  an  equal  bulk  of  oxygen  gas  supplies  its  place.  Now, 
since  carbonic  acid  gas  contains  just  its  own  bulk  of  oxygen,  it  is 
evident  that  what  has  thus  been  decomposed  in  the  leaves  has  re- 
turned all  its  oxygen  to  the  air.  Plants  take  carbonic  acid  from 
the  atmosphere,  therefore  (directly  or  indirectly) ;  they  retain  its 
carbon  ;  they  give  back  its  oxygen.* 

349.  But  cellulose,  being  the  final,  insoluble  product  of  vegeta- 
tion appropriated  as  tissue,  cannot  itself  be  formed  in  the  first  in- 
stance. The  materials  from  which  it  is  deposited,  and  which  we 
actually  find  in  the  elaborated  sap,  are  Dextrine  pr  Vegetable  Mu- 
cilage (81,  83),  sugar  (84),  &c.  The  first,  of  these  is  probably 
directly  produced  in  assimilation.  Its  chemical  composition  is  the 
same  as  that  of  pure  cellulose  :  it  consists,  not  only  of  the  same 
three  elements,  but  of  the  same  elements  in  exactly  the  same  pro- 
portion. Dextrine,  vegetable  mucilage,  &c.,  are  the  primary,  as  yet 
unappropriated  materials  of  vegetable  tissue,  or  u«solidified  cellu- 
lose, and  their  production  from  the  crude  sap  is  attended  with  the 
evolution  of  the  oxygen  which  was  contained  in  the  carbonic  acid 
of  the  plant's  food,  as  already  stated.!     Nor  is  the  result  in  any 

*  At  least,  the  result  is  as  if  the  oxygen  exhaled  were  all  thus  detached 
from  the  carbon  of  the  carbonic  acid.  Just  this  amount  is  liberated,  and  the 
facts  obviously  point  to  the  carbonic  acid  as  its  real  source.  But,  on  the  other 
hand,  it  appears  unlikely  that  a  substance  which  holds  oxygen  with  such 
strong  affinity  as  carbon  should  yield  the  whole  of  it  under  these  circumstan- 
ces :  and  water  is  certainly  decomposed,  with  the  evolution  of  oxygen,  in  the 
formation  of  a  class  of  vegetable  products  soon  to  be  mentioned;  besides,  Ed- 
wards and  Colin  have  shown  that  water  is  directly  decomposed  during  germi- 
nation. Still,  as  no  one  supposes  that  the  residue  after  the  liberation  of  oxy- 
gen is  carbon  and  water,  but  only  the  three  elements  in  the  proportions  which 
would  constitute  them,  it  amounts  to  nearly  the  same  thing  whether  we  say 
that  the  oxygen  of  the  carbonic  acid,  or  an  amount  of  oxygen  equivalent  to  that 
of  the  carbonic  acid,  derived  partly  from  it  and  partly  from  the  tcater,  is  liber- 
ated in  such  cases.  That  Schleiden  should  assert  that  the  oxygen  liberated 
comes  from  the  decomposition  of  water  alone,  shows  gross  carelessness,  or  an 
ignorance  of  the  elements  of  arithmetic  as  well  as  chemistry,  which  is  the  less 
excusable  in  one  who,  in  a  scientific  treatise,  habitually  applies  opprobrious 
epithets  to  a  great  part  of  his  fellow-laborers. 

t  The  result  is  just  the  same,  if,  with  Henfrey,  we  suppose  that  the  mat- 
17* 


m 


THE    FOOD    AND    NUTRITION    OF    PLANTS. 


respect  altered  when  Starch  is  produced.  In  that  case,  the  direct 
product  of  assimilation  in  the  form  of  dextrine,  instead  of  being 
immediately  appropriated  in  growth,  is  solidified  in  the  starch- 
grains,  and  in  that  compact  and  temporarily  insoluble  form  accu- 
mulated as  the  ready  prepared  materials  of  future  growth  (81). 
So,  also,  when  Inuline  is  formed  instead  of  starch,  as  in  the  roots 
of  Elecampane  (Inula  Helenium)  and  the  Dahlia,  and  the  tubers 
of  the  Jerusalem  Artichoke :  here  the  dextrine  is  solidified  into  a 
substance  intermediate  in  its  properties  between  dextrine  and  cel- 
lulose, which  is  closely  analogous  to  starch,  and  subservient  to  the 
same  purpose.  Notwithstanding  the  difference  in  their  properties 
and  chemical  reactions,  these  various  products  are  strictly  isomeric^ 
that  is,  they  consist  of  the  same  elements,  combined  in  the  same 
proportions ;  and  physiologically  they  are  merely  different  states 
of  one  and  the  same  thing.  Dextrine  is  the  most  soluble  state 
(dissolving  freely  in  cold  water),  and  that  originally  formed  in  as- 
similation in  the  foliage  :  starch  and  inuline  are  two  temporarily 
solidified  states,  and  cellulose  is  the  ultimate  and  usually  perma- 
nent insoluble  condition.  Accordingly,  whenever  the  materials  of 
growth  are  supplied  from  such  accumulations  of  nourishment,  as 
especially  from  the  seed  in  germination,  from  fleshy  roots  (128), 
rootstocks  (174),  tubers  (175),  &c.,  the  starch  or  inuline  is  dis- 
solved in  the  sap,  being  spontaneously  reconverted  into  dextrine, 
&c.,  and  attracted  in  this  liquid  state  into  the  growing  parts,  where 
it  is  transformed  into  cellulose,  and  becomes  a  portion  of  the  per- 
manent vegetable  fabric. 

350.  Assimilated  matter  also  occurs  in  the  sap  under  the  still 
more  soluble  form  of  Sugar  (84).  If  we  suppose  this  to  be  a  di- 
rect product  of  the  assimilation  of  carbonic  acid  and  water,  the 
amount  of  oxygen  gas  exhaled  will  be  just  the  same  as  before. 
For  sugar  has  the  same  elementary  composition  as  dextrine,  starch, 
and  cellulose,  with  the  addition  of  one  equivalent  of  water  in  the  case 
of  cane-sugar,  and  of  three  more  in  that  of  grape-sugar.*  If,  as  is 
more  probable,  sugar  is  a  subsequent  transformation  of  dextrine, 
then  the  latter  has  only  to  appropriate  some  water.     In  the  forma- 


ters  acted  upon  in  assimilation  are  at  first  as  much  deoxidized  as  in  chloro- 
phyll, since  these  general  products  of  vegetation  have  immediately  to  absorb 
oxygen  enough  to  bring  them  to  the  form  of  dextrine,  starch,  cellulose,  &c. 
*  The  formula  for  cane-sugar  is  C^^,  H^^,  O^^;  for  grape-sugar,  C^^,  H'^,  O'^ 


ASSIMILATION.  199 

tion  of  all  these  products,  therefore,  the  same  quantity  of  carbonic 
acid  is  consumed,  and  all  its  oxygen  restored  to  the  air.*  It  is 
more  and  more  evident,  therefore,  that,  by  just  so  much  as  plants 
grow,  they  take  carbonic  acid  from  the  air,  they  retain  its  carbon, 
and  return  its  oxygen. 

351.  In  the  production  of  that  modification  of  cellulose  called 
Lignine  (41),  which  forms  a  secondary  deposit  thickening  the  walls 
of  the  cells,  and  which  abounds  in  wood,  if  this  be  really  a  simple 
product,  and  not  a  mixture,  not  only  must  a  larger  amount  of  car- 
bonic acid  be  decomposed,  but  a  small  portion  of  water  also, 
with  the  liberation  of  Us  oxygen.  For  the  composition  attributed 
to  it  shows  that  it  contains  less  oxygen  than  would  suffice  to  con- 
vert its  hydrogen  into  water,  t  This  excess  of  hydrogen,  and  the 
still  larger  excess  of  carbon,  renders  those  woods  that  abound  with 
incrusting  deposit,  other  things  being  equal,  more  valuable  as  fuel 
than  those  of  which  the  tissue  in  great  part  consists  of  proper  cellu- 
lose, as  has  already  been  stated. 

352.  The  whole  class  of  fatty  substances,  including  the  Oils, 
Wax,  Chlorophyll  (85-87),  and  most  of  the  products  of  their  alter- 

*  Since  all  these  neutral  ternary  substances  are  identical,  or  nearly  so,  in  ele- 
mentary composition,  and  since,  with  the  same  amount  of  carbon,  derived 
from  the  decomposition  of  carbonic  acid,  the  plant  can  form  them  all,  not- 
withstanding the  great  difference  in  their  external  characters,  it  will  no  longer 
appear  so  surprising  that  they  should  be  so  readily  convertible  into  each  other 
in  the  living  plant,  and  even  in  the  hands  of  the  chemist.  But  the  chemistry 
of  organic  nature  exceeds  the  resources  of  science,  and  constantly  produces 
transformations  which  the  chemist  in  his  laboratory  is  unable  to  effect.  The 
latter  can  change  starch  into  dextrine,  and  dextrine  into  sugar;  but  he  cannot 
reverse  the  process,  and  convert  sugar  into  dextrine,  or  dextrine  into  starch. 
In  the  plant,  however,  all  these  various  transformations  are  continually  taking 
place.  Thus,  the  starch  deposited  in  the  seed  of  the  Sugar-cane,  as  in  all 
other  Grasses,  is  changed  into  sugar  in  germination  :  and  the  sugar  which  fills 
the  tissue  of  the  stem  at  the  time  of  flowering  is  rapidly  carried  into  the  flow- 
ers, where  a  portion  is  transformed  into  starch  and  again  deposited  in  the 
newly-formed  seeds.  And  although  the  chemist  is  unable  to  transform 
starch,  sugar,  &c.  into  cellulose,  yet  he  readily  effects  the  opposite  change, 
by  reconverting  woody  fibre,  &c.  (under  the  influence  of  sulphuric  acid)  into 
dextrine  and  sugar.  The  plant  does  the  same  thing  in  the  ripening  of  fruits, 
during  which  a  portion  of  tissue  is  often  transformed  into  sugar.  Starch-grains 
and  cellulose  never  can  be  formed  artificially,  because  they  are  not  merely 
organizable  matter,  but  have  an  organic  structure,  or  are  the  result  of  growth. 

t  According  to  Payen,  lignine,  separated  as  much  as  possible  from  cellulose, 
consists  of  Carbon  53.8,  Hydrogen  60,  and  Oxygen  40.2  per  cent.,  =f=  C^^  11^^, 


200  THE    FOOD    AND    NUTRITION    OF    PLANTS. 

ation,  contain,  a  few  of  them  no  oxygen  at  all  (such  as  caoutchouc 
and  some  oils),  and  all  of  them  less  oxygen  than  is  requisite  to  con- 
vert their  hydrogen  into  water.  In  their  direct  formation,  there- 
fore, not  only  all  the  oxygen  of  the  carbonic  acid  has  been  given 
out,  but  also  a  portion  belonging  to  the  water.  If  formed  by  a 
further  deoxidation  of  neutral  ternary  products,  as  chlorophyll  from 
starch  (87)  and  wax  from  sugar  (86),  the  same  result  is  attained 
as  respects  the  liberation  of  oxygen  gas,  but  by  two  or  more  steps 
instead  of  one.  The  Resins^  doubtless,  are  not  direct  vegetable 
products,  but  originate  from  the  alteration  and  partial  oxidation  of 
the  essential  oils.  Balsams,  which  exude  from  the  bark  of  cer- 
tain plants,  are  natural  solutions  of  resins  in  their  essential  oils,  as 
rosin,  or  pine-resin,  in  the  oil  of  turpentine. 

353.  An  opposite  class,  the  Vegetahle  Acids  (90),  contain  more 
oxygen  than  is  necessary  for  the  conversion  of  their  hydrogen  into 
water,  but  less  than  the  amount  which  exists  in  carbonic  acid  and 
water.  Indeed  the  most  general  vegetable  acid,  the  oxalic  (which 
is  formed  artificially  by  the  action  of  nitric  acid  on  starch),  has  no 
hydrogen,  except  in  the  atom  of  water  that  is  connected  with  it. 
These  acids  are  sometimes  formed  in  the  leaves,  as  in  the  Sorrel, 
the  Grape-vine,  &c.,  but  usually  in  the  fruit.  If  produced  directly 
from  the  sap,  as  is  probably  the  case  in  acid  leaves,  only  a  part  of 
the  oxygen  in  the  carbonic  acid  which  contributes  to  their  forma- 
tion would  be  exhaled.  But  if  they  are  formed  from  sugar,  or  any 
other  of  the  general  products  of  the  proper  juice,  the  absorption  of 
a  portion  of  oxygen  from  the  air  would  be  required  for  the  conver- 
sion ;  and  this  absorption  takes  place  (at  least  in  some  cases)  when 
fruits  acquire  their  acidity.  Even  their  formation  by  the  plant, 
therefore,  is  attended  by  the  liberation  of  oxygen  gas,  though  less 
in  quantity  than  in  ordinary  vegetation, 

354.  There  is  still  another  class  of  vegetable  products  of  uni- 
versal occurrence,  and,  although  comparatively  small  in  quantity, 
of  as  high  importance  as  those  which  constitute  the  permanent 
fabric  of  the  plant ;  namely,  the  neutral  quaternary  organic  com- 
pounds, of  which  nitrogen  is  a  constituent  (79).  These  are  mutu- 
ally convertible  bodies,  related  to  each  other  as  dextrine  and  sugar 
to  starch  and  cellulose,  and  playing  the  same  part  in  the  animal 
economy  that  the  neutral  ternary  products  do  in  the  vegetable. 
To  the  basis  or  type  of  these  azotized  products  Mulder  has  given 
the  name  o^  Proteine  (27)  :  hence  they  are  sometimes  collectively 


ASSIMILATION.  201 

called  proteine  compounds.  In  their  production  from  the  crude 
sap,  the  ammonia,  or  other  azotized  matter  it  contains,  plays  an 
essential  part ;  and  oxygen  gas  is  restored  to  the  air  from  the  de- 
composition of  all  the  carbonic  acid  concerned  and  a  part  of  the 
water.* 

355.  In  living  cells  the  proteine  exists  as  azotized  mucilage,  and 
forms  the  protoplasm  or  vitally  active  lining  which  may  be  said  to 
give  origin  to  the  vegetable  structure,  since  the  cellulose  is  depos- 
ited, under  its  influence  to  form  the  permanent  walls  or  fabric  of 
the  cells,  as  has  already  been  explained  (27-32).  When  the 
cells  have  completed  their  growth  and  transformation,  the  proto- 
plasm abandons  them,  being  constantly  attracted  onwards  into 
forming  and  growing  parts,  where  it  incites  new  development.  For 
this  azotized  matter  has  the  remarkable  peculiarity  of  inducing 
chemical  changes  in  other  organic  products,  especially  the  neutral 
ternary  bodies,  causing  one  kind  to  be  transformed  into  another,  or 
even  the  decomposition  of  a  part  into  alcohol,  acetic  acid,  and 
finally  into  carbonic  acid  and  water  (as  in  germination,  &c.), —  it- 
self remaining  the  while  essentially  unaltered. 

356.  The  constant  attraction  of  the  protoplasm  from  the  com- 
pleted into  the  forming  parts  of  the  plant  explains  how  it  is,  that 
so  small  a  percentage  of  azotized  matter  should  be  capable  of 
playing  such  an  all-important  part  in  the  vegetable  economy.  It 
does  its  work  with  httle  loss  of  material,  and  no  portion  of  it  is 
fixed  in  the  tissues.  At  least,  the  little  that  remains  in  old  parts  is 
capable  of  being  washed  out,  showing  that  it  forms  no  integral  part 
of  the  fabric.  It  explains  why  the  heart-wood  of  trees,  especially 
the  most  solidified  kinds,  yields  barely  a  trace  of  nitrogen,  while 
the  sap-wood  yields  an  appreciable  amount,  and  the  cambium-layer 

*  The  chemical  changes  have  been  tabulated  thus:  — 

From  which  are  formed  the  product : 

C.  H.    N.    O. 

1  of  Proteine,        48  36    6       14 

4  of  Cellulose,       48  40  40 

212  of  Oxygen  lib- 
erated, 212 


The  materials : 

C. 

H. 

N. 

O. 

74 

of  Water, 

74 

74 

94  of  Carbonic  acid,  94 

188 

2 

of  Carbonate 

of 

ammonia, 

2 

2 

6 

4 

96    76    6    266  96    76    6    266 

It  seems  now  to  be  conceded,  that  proteine,  as  well  as  all  its  transformations 
or  stales,  contains  also,  as  essential  constituents,  a  minute  quantity  of  sulphur 
and  phosphorus,  one  or  both  (10). 


202  THE    FOOD   AND   NUTRITION    OF    PLANTS. 

and  all  parts  of  recent  formation,  such  as  the  buds,  young  shoots, 
and  rootlets,  always  contain  several  hundredths  of  it.  This  gives 
the  reason,  also,  why  sap-wood  is  so  liable  to  decay  (induced  by 
the  proteine),  and  the  more  liable  in  proportion  to  its  newness  and 
the  quantity  of  sap  it  contains,  while  the  perfectly  lignified  heart- 
wood  is  so  durable.  Following  this  course,  we  find  that  the  az- 
otized  matter  rapidly  diminishes  in  the  stem  and  herbage  during 
flowering,  while  it  accumulates  in  the  forming  fruit,  and  is  finally 
condensed  in  the  seeds  (which  have  a  larger  percentage  than 
any  other  organ),  ready  to  subserve  the  same  office  in  the  devel- 
opment of  the  embryo  plant  it  contains.* 

357.  When  wheat-flour,  kneaded  into  dough,  is  subjected  to  the 
prolonged  action  of  water,  the  starch  is  washed  away,  and  a  tena- 
cious, elastic  residue,  the  Gluten  of  the  flour,  which  gives  it  the 
capability  of  being  raised,  contains  nearly  all  the  proteine  com- 
pounds of  the  seed,  mixed  with  some  fatty  matters  (which  may  be 
removed  by  alcohol  and  ether)  and  with  a  little  cellulose.  The 
azotized  products  constitute  from  eight  to  thirty  per  cent,  of  the 
weight  of  wheat-flour  ;  the  proportion  varying  greatly  under  difier- 
ent  circumstances,  but  always  largest  when  the  soil  is  best  supplied 
with  manures  that  abound  in  nitrogen.  The  gluten  is  not  itself  a 
simple  quaternary  principle  ;  but  is  a  mixture  of  four  nearly  isom- 
eric bodies  of  this  sort,  distinguished  by  chemists  under  the  names 
Fibrine  (identical  in  nature  with  that  which  forms  the  muscles  of 
animals).  Albumen  (of  the  same  nature  as  animal  albumen),  Ca- 
seine  (identical  with  the  curd  of  milk),  and  Glutine.  In  beans  and 
all  kinds  of  pulse,  or  seeds  of  Leguminous  plants,  the  large  pro- 
portion of  azotized  matter  principally  occurs  in  the  form  of  Legu- 
mine,  a  form  nearly  intermediate  in  character  between  albumen 
and  caseine. 

358.  Having  now  noticed  all  the  principal  products  of  assimila- 
tion in  plants,  at  least  those  concerned  in  nutrition,  as  compared 
with  the  inorganic  materials  from  which  they  must  needs  be 
formed,  we  may  the  more  clearly  perceive,  that  the  principal  re- 
sult of  vegetation,  as  concerns  the  atmosphere,  from  which  plants 
draw  their  food,  consists  in  the  withdrawal  of  water,  of  a  little  am- 


*  The  cotyledons  of  peas  and  beans,  according  to  Mr.  Rigg,  contain  from 
100  to  140  parts,  and  the  plumule  abcut  200  parts,  of  nitrogen  to  1,000  parts  of 
carbon. 


INFLUENCE    OF    VEGETATION    ON    THE    ATMOSPHERE.  203 

monia,  and  of  a  large  proportion  of  carbonic  acid,  with  the  restora- 
tion of  oxygen.  The  latter  is  a  constant  effect  of  vegetation  and  the 
measure  of  its  amount.  As  respects  the  tissue  of  the  plant,  which 
makes  up  almost  the  whole  bulk  of  a  tree  or  other  vegetable  fabric, 
the  sole  consequences  of  its  formation  upon  the  air  are  the  with- 
drawal of  a  small  quantity  of  water,  and  of  a  large  amount  of  car- 
bonic acid  gas,  and  the  restoration  of  the  oxygen  of  the  latter.  In 
the  formation  of  the  azotized  products,  a  portion  of  ammonia  or  of 
some  equivalent  compound  of  nitrogen  is  also  withdrawn.  It  is 
true,  indeed,  that  leaves  decompose  carbonic  acid  only  in  daylight; 
and  that  they  sometimes  impart  a  quantity  of  carbonic  acid  to  the 
air  in  the  night,  especially  when  vegetation  languishes,  or  even  take 
from  it  a  little  oxygen.  But  this  does  not  affect  the  general  result, 
nor  require  any  qualification  of  the  general  statement.  The  work 
simply  ceases  when  light  is  withdrawn.  The  plant  is  then  merely 
in  a  passive  state.  Yet,  whenever  exhalation  from  the  leaves  slowly 
continues  in  darkness,  the  carbonic  acid  which  the  water  holds  ne- 
cessarily flies  off  with  it,  during  the  interruption  to  vegetation,  into 
the  atmosphere  from  which  the  plant  took  it.  So  much  of  the  crude 
sap,  or  raw  material,  merely  runs  to  waste.  Furthermore,  it  must 
be  remembered,  that  the  decomposition  of  carbonic  acid  in  vegeta- 
tion is  in  direct  opposition  to  ordinary  chemical  affinity;  or,  in  other 
words,  that  all  organized  matter  is  in  a  state  corresponding  to  that 
of  unstable  equilibrium.  Consequently,  when  light  is  withdrawn, 
ordinary  chemical  forces  may  perhaps  to  some  extent  resume  their 
sway,  the  oxygen  of  the  air  combine  with  some  of  the  newly  de- 
posited carbon  to  reproduce  a  little  carbonic  acid,  and  thus  demol- 
ish a  portion  of  the  rising  vegetable  structure  which  the  setting  sun 
left,  as  it  were,  in  an  unfinished  or  unstable  state.  This  is  what 
actually  takes  place  in  a  dead  plant  at  all  times,  and*  whenever  an 
herb  is  kept  in  prolonged  darkness ;  chemical  forces,  exerting  their 
power  uncontrolled,  demolish  the  whole  vegetable  fabric,  beginning 
with  the  chlorophyll  (as  we  observe  in  blanching  Celery),  and  at 
length  resolve  it  into  the  carbonic  acid  and  water  from  which  it 
was  formed.  But  this  must  all  be  placed  to  the  account  of  decom- 
posing^ not  of  growing  vegetation  ;  and  even  if  it  were  a  universal 
phenomenon,  which  is  by  no  means  the  case,*  would  not  affect  the 

*  In  repeating  the  old  experiments  upon  this  subject  with  due  precautions, 
and  with  improved  means  of  research,  it  is  found  that  many  ordinary  plants, 


204  THE  FOOD  AND  NUTRITION  OF  PLANTS. 

general  statement,  that,  hy  so  much  as  plants  grow,  they  decom- 
pose carbonic  acid  and  give  its  oxygen  to  the  air ;  or,  in  other 
words,  purify  the  air. 

359.  Every  six  pounds  of  carbon  in  existing  plants  has  with- 
drawn twenty-two  pounds  of  carbonic  acid  gas  from  the  atmos- 
phere, and  replaced  it  with  sixteen  pounds  of  oxygen  gas,  occupy- 
ing the  same  bulk.  To  form  some  general  conception  of  the 
extent  of  the  influence  of  vegetation  upon  the  air  we  breathe, 
therefore,  we  should  compute  the  quantity  of  carbon,  or  charcoal, 
that  is  contained  in  the  forests  and  herbage  of  the  world,  and  add 
to  the  estimate  all  that  exists  in  the  soil  as  vegetable  mould,  peat, 
and  in  other  forms ;  all  that  is  locked  up  in  the  vast  deposits  of 
coal  (the  product  of  the  vegetation  of  bygone  ages)  ;  and,  finally, 
all  that  pertains  to  the  whole  existent  animal  kingdom  ;  —  and  we 
shall  have  the  aggregate  amount  of  a  single,  though  the  largest, 
element  which  vegetation  has  withdrawn  from  the  atmosphere.    By 


when  in  full  health  and  vigorous  yegetation,  impart  no  carbonic  acid  to  the  air 
during  the  night.  —  See  Pepys,  in  Philosophical  Transactions,  for  1843. — 
They  deteriorate  the  air  only  in  their  decay,  and  in  peculiar  processes,  dis- 
tinct from  vegetation  and  directly  the  reverse  of  assimilation ;  as  in  germina- 
tion, for  instance,  where,  as  will  hereafter  be  explained,  the  proteine  induces 
the  decomposition  of  a  portion  of  the  store  of  assimilated  matter,  in  order  that 
the  rest  may  be  brought  into  a  serviceable  condition.  For  at  the  beginning,  it 
must  be  recollected,  the  plant  or  the  shoot  growls,  not  by  assimilation,  but  by 
consuming  and  appropriating  a  store  of  nourishment  which  was  assimilated  by 
the  parent.  The  evolution  of  carbonic  acid  by  plants,  therefore,  which  has  so 
long  been  taken  for  granted,  and  misinterpreted,  has  no  existence  as'a  gen- 
eral phenomenon.  And  it  is  by  a  false  analogy  that  this  loss  which  plants  sus- 
tain in  the  night  has  been  dignified  with  the  name  of  vegetable  respiration, 
and  vegetables  said  to  vitiate  the  atmosphere,  just  like  animals,  by  their  respi- 
ration, while  they  purify  it  by  their  digestion.  If,  indeed,  this  were  a  con- 
stant function,  in  any  way  contributing  to  maintain  the  life  and  health  of  the 
plant,  it  might  be  properly  enough  compared  with  the  respiration  of  animals, 
which  is  itself  a  decomposing  operation.  But  this  is  not  the  case.  And  herein 
is  a  characteristic  difference  between  vegetables  and  animals  :  the  tissues  of  the 
latter  continue  to  live  and  act  through  the  lifetime  of  the  animal,  and  there- 
fore require  constant  interstitial  renewal  by  nutrition,  new  particles  replacing 
the  old,  which  are  removed  and  restored  to  the  mineral  world  by  respiration: 
while  in  plants  there  is  no  such  renewal,  but  the  fabric  once  completed  re- 
mains unchanged,  ceases  to  be  nourished,  and  consequently  soon  loses  its  vital- 
ity ;  while  new  parts  are  continually  formed  farther  on  to  take  their  places,  to 
be  in  turn  abandoned.  Plants,  therefore,  having  no  decomposition  and  recom- 
position  of  any  completed  fabric,  cannot  have  the  function  of  respiration. 


INFLUENCE    OF    VEGETATION    ON    THE    ATMOSPHERE.  205 

multiplying  this  vast  amount  of  carbon  by  sixteen,  and  dividing  it 
by  six,  we  obtain  an  expression  of  the  number  of  pounds  of  oxy- 
gen gas  that  have  in  this  process  been  supplied  to  the  atmosphere. 
360.  Rightly  to  understand  the  object  and  consequences  of  this 
immense  operation,  which  has  been  going  on  ever  since  vegetation 
began,  it  should  be  noted,  that,  so  far  as  we  know,  veigetation  is 
the  only  operation  in  nature  which  gives  to  the  air  free  oxygen  gas, 
that  indispensable  requisite  to  animal  life.  There  is  no  other  pro- 
vision for  maintaining  the  supply.  The  prevailing  chemical  ten- 
dencies, on  the  contrary,  take  oxygen  from  the  air.  Few  of  the 
materials  of  the  earth's  crust  are  saturated  with  it ;  some  of  them 
still  absorb  a  portion  from  the  air  in  the  changes  they  undergo ; 
and  none  of  them  give  it  back  in  the  free  state  in  which  they  took 
it,  —  in  a  state  to  support  animal  life,  —  by  any  known  natural 
process,  at  least  upon  any  considerable  scale.  Animals  all  con- 
sume oxygen  at  every  moment  of  their  life,  giving  to  the  air  car- 
bonic acid  in  its  room ;  and  when  dead,  their  decaying  bodies  con- 
sume still  more.  Decomposing  vegetable  matter  produces  the 
same  result.  Its  carbon,  taking  oxygen  from  the  air,  is  likewise 
restored  in  the  form  of  carbonic  acid.  Combustion,  as  in  burning 
our  fuel,  amounts  to  precisely  the  same  thing ;  it  is  merely  rapid 
decay.  The  carbon  which  the  trees  of  the  forest  have  gathered 
from  the  air  in  the  course  of  centuries,  their  prostrate  decaying 
trunks  may  almost  as  slowly  restore  to  the  air,  in  the  original  form 
of  carbonic  acid.  But  if  set  on  fire,  the  same  result  may  be  accom- 
plished in  a  day.  All  these  causes  conspire  to  rob  the  air  of  its 
life-sustaining  oxygen.  The  original  supply  is  indeed  so  vast,  that, 
were  there  no  natural  compensation,  centuries  upon  centuries 
would  elapse  before  the  amount  of  oxygen  could  be  so  much  re- 
duced, or  that  of  carbonic  acid  increased,  as  to  affect  the  existence 
of  the  present  races  of  animals.  But  such  a  period  would  eventu- 
ally arrive,  were  there  no  natural  provision  for  the  decomposition 
of  the  carbonic  acid  constantly  poured  into  the  air  from  these  va- 
rious sources,  and  for  the  restoration  of  its  oxygen.  We  have 
seen  that  vegetation  accomplishes  this  very  result.  The  needful 
compensation  is  therefore  found  in  the  vegetable  kingdom.  While 
animals  consume  the  oxygen  of  the  air,  and  give  back  carbonic 
acid  which  is  injurious  to  their  life,  this  carbonic  acid  is  the  prin- 
cipal element  of  the  food  of  vegetables,  is  consumed  and  decom- 
posed by  them,  and  its  oxygen  restored  for  the  use  of  animals. 
18 


206  THE    FOOD   AND    NUTRITION    OF    PLANTS. 

Hence  the  perfect  adaptation  of  the  two  great  kingdoms  of  living 
beings  to  each  other ;  —  each  removing  from  the  atmosphere  what 
would  be  noxious  to  the  other  ;  —  each  yielding  to  the  atmosphere 
what  is  essential  to  the  continued  existence  of  the  other.* 

361.  The  relations  of  simple  vegetation,  under  this  aspect,  to 
the  mineral  kingdom  on  the  one  hand  and  the  animal  kingdom  on 
the  other,  are  simply  set  forth  in  the  first  part  of  the  diagram  placed 
at  the  close  of  this  chapter. 

362.  But,  besides  this  remotely  essential  office  in  purifying  the 
air,  the  vegetable  kingdom  renders  to  the  animal  another  service 
so  immediate,  that  its  failure  for  a  single  year  would  nearly  depop- 
ulate the  earth ;  namely,  in  providing  the  necessary  food  for  the 
whole  animal  kingdom.  It  is  under  this  view,  that  the  grand  office 
of  vegetation  in  the  general  economy  of  the  world  is  to  be  contem- 
plated. Plants  are  the  sole  producers  of  nourishment.  They  alone 
transform  mineral,  chiefly  atmospheric  materials,  they  condense  air, 
into  organized  matter.  While  they  thus  produce  upon  a  vast  scale, 
they  consume  or  destroy  comparatively  little  ;  and  this  never  in 
proper  vegetation,  but  in  some  special  processes  hereafter  to  be  con- 
sidered (370).  Often  when  they  appear  to  consume  their  own  prod- 
ucts, they  only  transform  and  transfer  them  (128,  174),  as  when 
the  starch  of  the  Potato  is  converted  into  new  shoots  and  foliage. 

363.  Animals  consume  what  vegetables  produce.  They  them- 
selves produce  nothing  directly  from  the  mineral  world.  The 
herbivorous  animals  take  from  vegetables  the  organized  matter 
which  they  have  produced ;  —  a  part  of  it  they  consume,  and  in 
respiration  restore  the  materials  to  the  atmosphere  from  which 
plants  derived  them,  in  the  very  form  in  which  they  were  taken, 
namely,  as  carbonic  acid  and  water.  The  portion  they  accumu- 
late in  their  tissues  constitutes  the  food  of  carnivorous  animals  ;  who 
consume  and  return  to  the  air  the  greater  part  during  life,  and  the 

*  It  is  plain,  however,  that,  while  the  animal  kingdom  is  entirely  depend- 
ent on  the  vegetable,  as  no  function  of  animals  restores  to  the  atmosphere  the 
oxygen  they  consume,  yet  the  latter  is,  in  a  good  degree  at  least,  independent 
of  the  former,  and  might  have  existed  alone.  The  decaying  races  of  plants, 
giving  back  their  carbon  to  the  air  and  to  the  soil  (333)  would  furnish  food  for 
their  successors.  And  since  all  the  carbonic  acid  which  animals  render  to  the 
air  in  respiration  they  have  derived  from  their  vegetable  food,  it  would  in 
time  have  found  its  way  back  to  the  air,  for  the  use  of  new  generations  of 
plants,  without  the  intervention  of  animals.  At  most,  they  merely  expedite 
its  return. 


RELATIONS  OF  THE  VEGETABLE  TO  THE  ANIMAL  KINGDOM.       207 

remainder  in  decay  after  death.  The  atmosphere,  therefore,  out 
of  which  plants  create  nourishment,  and  to  which  animals  as  they 
consume  return  it,  forms  the  necessary  link  between  the  animal 
and  vegetable  kingdoms,  and  completes  the  great  cycle  of  organic 
existence.  Organized  matter  passes  through  various  stages  in  veg- 
etables, through  others  in  the  herbivorous  animals,  and  undergoes 
its  final  transformations  in  the  carnivorous  animals.  Portions  are 
consumed  at  every  stage,  and  restored  to  the  mineral  kingdom,  to 
which  the  whole,  having  accomplished  its  revolution,  finally  returns. 
364.  Plants  not  only  furnish  all  the  materials  of  the  animal  fab- 
ric, but  furnish  each  principal  constituent  ready-formed,  so  that  the 
animal  has  only  to  appropriate  it.  The  food  of  animals  is  of  two 
kinds  ;  — 1.  that  which  serves  to  support  respiration  and  maintain  the 
animal  heat ;  2.  that  which  is  capable  of  forming  a  portion  of  the 
animal  fabric,  of  its  flesh  and  bones.  The  ternary  vegetable  prod- 
ucts furnish  the  first,  in  the  form  of  sugar,  vegetable  jelly,  starch, 
oil,  &c.,  and  even  cellulose;  substances  which,  containing  no  ni- 
trogen, cannot  form  a  part  of  the  animal  frame,  but,  conveyed  into 
the  blood,  are  decomposed  in  respiration,  the  carbon  and  the  ex- 
cess of  hydrogen  combining  with  the  oxygen  of  the  air,  to  which 
they  are  restored  in  the  form  of  carbonic  acid  and  water.  Any 
portion  not  required  by  the  immediate  demands  of  respiration  is 
stored  in  the  tissues  in  the  form  of  fat,  (which  the  animal  may 
either  accumulate  directly  from  the  oily  and  waxy  matters  in  its 
vegetable  food,  or  produce  by  an  alteration  of  the  starch  and  su- 
gar,) as  a  provision  for  future  use  ;  any  deficiency  subjects  the  tis- 
sues themselves,  or  the  proper  supporting  food,  to  immediate  de- 
composition in  respiration.  The  quaternary  or  azotized  products 
furnish  the  proper  materials  of  the  animal  frame,  the  fibrine,  ca- 
seine,  albumen,  &c.,  being  directly  appropriated  from  the  vegeta- 
ble food  to  the  blood,  muscles,  &c. ;  while  a  slight  transformation 
of  them  gives  origin  to  gelatine^  of  which  the  sinews,  cartilages, 
and  the  organic  part  of  the  bones  consist.  The  earthy  portion  of 
the  bones,  the  iron  in  the  blood,  and  all  the  saline  ingredients  of 
the  animal  body  (with  the  exception  of  common  salt,  which  is 
sometimes  taken  directly  from  the  mineral  kingdom),  are  drawn 
from  the  earthy  constituents  (336)  of  the  plants  upon  which  the 
animal  feeds.  The  animal  merely  appropriates  and  accumulates 
these  already  organizable  materials,  changing  them,  it  may  be,  little 
by  little,  as  he  destroys  them,  but  rendering  them  all  back  (those 


208 


DIAGRAM    OF    VEGETABLE    DIGESTION. 


of  the  first  class  through  the  lungs,  of  the  second  through  the  kid- 
neys) finally  to  the  earth  and  air  from  which,  and  in  the  condition 
in  which,  the  vegetable  took  them. 

365.  The  relations  of  vegetation  to  the  mineral  and  animal  king- 
doms, as  especially  concerns  the  elaboration  of  the  constituents  of 
the  animal  body,  are  shown  in  the  second  part  of  the  subjoined 
diagram. 


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FLOWERING  AN    EXHAUSTIVE   PROCESS.  209 

CHAPTER    YII. 

OF    FLOWERING    AND    ITS    CONSEQUENCES. 

366.  Plants  have  thus  far  been  considered  only  as  respects  their 
Organs  of  Vegetation ;  —  those  which  essentially  constitute  the 
vegetable  being,  by  which  it  grows,  deriving  its  support  from  the  sur- 
rounding air  and  soil,  and  converting  these  inorganic  materials  into 
its  own  organized  substance.  As  every  additional  supply  of  nour- 
ishment furnishes  materials  for  the  development  of  new  branches, 
roots,  and  leaves,  thus  multiplying  both  those  organs  which  receive 
food,  and  those  which  assimilate  it,  it  would  seem  that,  apart  from 
accidents,  the  increase  and  extension  of  plants  would  be  limited 
only  by  the  failure  of  an  adequate  supply  of  nourishment.  After 
a  certain  period,  however,  varying  in  different  species,  but  nearly 
constant  in  each,  a  change  ensues,  which  controls  this  otherwise 
indefinite  extent  of  the  branches,  and  is  attended  with  very  impor- 
tant results.  A  portion  of  the  buds,  instead  of  elongating  into 
branches,  are  developed  in  the  form  of  Flowers  ;  and  the  nour- 
ishment, which  would  otherwise  contribute  to  the  general  increase 
of  the  plant,  is  partially  or  wholly  expended  in  their  production, 
and  in  the  maturation  of  the  fruit  and  seeds  (110).  So  far  as  we 
know,  the  sole  office  of  the  flower  and  fruit  in  the  vegetable  econ- 
omy is  the  production  of  seed.  Hence  they  are  termed  Organs 
OF  Reproduction  (115). 

367.  Flowering  an  Exhanslive  Process.  Plants  begin  to  bear  flow- 
ers at  a  nearly  determinate  period  for  each  species ;  which  is  de- 
pendent partly  upon  constitutional  causes  that  we  are  unable  to 
account  for,  and  partly  upon  the  requisite  supply  of  nutritive  mat- 
ter in  their  system.  For,  since  the  flower  and  fruit  draw  largely 
upon  the  powers  and  nourishment  of  the  plant,  while  they  yield 
nothing  in  return,  fructification  is  an  exhaustive  process,  and  a  due 
accumulation  of  food  is  requisite  to  sustain  it.*     Annuals  flower 

*  When  the  branch  of  a  fruit-tree,  which  is  sterile  or  does  not  perfect  its 
blossoms,  is  ringed  or  girdled  (by  the  removal  of  a  narrow  ring  of  bark),  the 
elaborated  juices,  being  arrested  in  their  downward  course,  are  accumulated 
in  the  branch,  which  is  thus  enabled  to  produce  fruit  abundantly ;  while  the 
shoots  that  appear  below  the  ring,  being  fed  only  by  the  crude  ascending  sap, 
18* 


210  FLOWERING   AND    ITS    CONSEQUENCES. 

in  a  few  weeks  or  months  after  they  spring  from  the  seed,  when 
they  have  little  nourishment  stored  up  in  their  tissue ;  and  their 
lives  are  destroyed  in  the  process  (127)  :  biennials  flower  after  a 
longer  period,  rapidly  exhausting  the  nourishment  accumulated  in 
the  root  during  the  previous  season,  and  then  perishing  (128); 
while  shrubs  and  trees  do  not  commence  flowering  until  they  are 
sufficiently  established  to  endure  it.  The  exhaustion  consequent 
upon  flowering,  however,  is  often  exhibited  in  fruit-trees,  which, 
after  producing  an  excessive  crop  (especially  of  late  fruits,  such  as 
apples),  sometimes  fail  to  bear  the  succeeding  year.  When  the 
crop  of  one  year  is  destroyed,  the  nourishment  which  it  would  have 
consumed  accumulates,  and  the  tree  may  bear  more  abundantly 
the  following  season,  and  so  on  alternately  from  year  to  year. 

368.  The  actual  consumption  of  nourishment  in  flowe'ring  may 
be  shown  in  a  variety  of  ways  ;  as  by  the  rapid  disappearance  of 
the  farinaceous  or  saccharine  store  in  the  roots  of  the  Carrot,  Beet, 
&c.,  when  they  begin  to  flower,  leaving  them  light,  dry,  and  empty  ; 
and  from  the  rapid  diminution  of  the  sugar  in  the  stalk  of  the  Sugar- 
cane (as  also  in  that  of  Maize)  at  the  same  period.  The  stalks 
are  therefore  cut  for  making  sugar  just  before  the  flowers  expand, 
as  they  then  contain  the  greatest  amount  of  saccharine  matter. 

369.  The  consequences  of  this  exhaustion  upon  the  duration  of 
plants  have  already  been  adverted  to.  They  are  further  illustrated 
by  the  facility  with  which  annuals  may  be  changed  into  biennials, 
or  their  life  prolonged  indefinitely,  by  preventing  their  flowering ; 
while  they  perish  whenever  they  bear  flowers  and  seed,  whether 
during  the  first  or  any  succeeding  year.  So,  a  common  annual 
Larkspur  has  given  rise  to  a  double-flowered  variety  in  the  gardens, 
which  bears  no  seed,  and  has  therefore  become  a  perennial.  So, 
also,  cabbage-stumps,  which  are  planted  for  seed,  may  be  made  to 
bear  heads  the  second  year  by  destroying  the  flower-shoots  as  they 
arise ;  and  the  process  may  be  continued  from  year  to  year,  thus 
converting  a  biennial  into  a  kind  of  perennial  plant.  The  effect  of 
flowering  upon  the  longevity  of  the  individual  is  strikingly  shown 

do  not  bear  flowers,  but  push  forth  into  leafy  branches.  So  the  flowers  of 
most  trees  and  shrubs  that  bear  large  or  fleshy  fruit  are  produced  from  lateral 
buds,  resting  directly  upon  the  wood  of  the  previous  year,  in  which  a  quantity 
of  nutritive  matter  is  deposited.  So,  also,  a  seedling  shoot,  which  would  not 
flower  for  several  years  if  left  to  itself,  blossoms  the  next  season  when  in- 
serted as  a  graft  into  an  older  trunk,  from  whose  accumulated  stock  it  draws. 


CONSUMPTION    IN    FLOWERING.  211 

by  the  Agave,  or  Century-plant,  —  so  called  because  it  flowers  in 
our  conservatories  only  after  the  lapse  of  a  hundred,  or  at  least  a 
great  number  of  years ;  although,  in  its  native  sultry  clime,  it 
generally  flowers  when  five  or  six  years  old.  But  whenever  this 
occurs,  the  sweet  juice  with  which  it  is  filled  at  the  time  (which 
by  fermentation  forms  pulque^  the  inebriating  drink  of  the  Mexi- 
cans) is  consumed  at  a  rate  correspondent  to  the  astonishing  rapid- 
ity with  which  its  huge  flower-stalk  shoots  forth  (24),  and  the  whole 
plant  inevitably  perishes  when  the  seeds  have  ripened.  So,  also, 
the  Corypha,  or  Talipot-tree,  a  magnificent  Oriental  Palm,  which 
lives  to  a  great  age  and  attains  an  imposing  altitude  (bearing  a 
crown  of  leaves,  each  blade  of  which  is  often  thirty  feet  in  circum- 
ference), flowers  only  once  ;  but  it  then  bears  an  enormous  num- 
ber of  blossoms,  succeeded  by  a  crop  of  nuts  sufficient  to  supply 
a  large  district  with  seed ;  while  the  tree  immediately  perishes 
from  the  exhaustion  consequent  upon  this  over-production. 

370.  Flowering  and  fruiting,  then,  draw  largely  upon  the  plant's 
resources,  while  they  give  back  nothing  in  return.  In  these  opera- 
tions, as  also  in  germination,  vegetables  act  as  true  consumers  (like 
animals,  363),  decomposing  their  own  products,  and  giving  back 
carbonic  acid  and  water  to  the  air,  instead  of  taking  these  materials 
from  the  air.  It  is  in  flowering  that  they  actually  consume  most. 
In  fruiting,  although  the  plant  is  robbed  of  a  large  quantity  of  nour- 
ishment, this  is  mostly  accumulated  in  the  fruit  and  seed,  in  a  con- 
centrated form,  for  the  future  consumption,  not  of  the  parent  plant, 
but  of  the  new  individual  inclosed  in  the  seed.  As  we  may  treat 
of  the  latter  elsewhere,  we  have  here  to  contemplate  only  the  real 
and  immediate  consumption  of  nourishment  by  the  flower. 

371.  This  is  shown  by  the  action  of  flowers  upon  the  air,  so  dif- 
ferent from  that  of  leaves.  While  the  foliage  withdraws  carbonic 
acid  from  the  air,  and  restores  oxygen  (346,  358),  flowers  take  a 
small  portion  of  oxygen  from  the  air,  and  give  back  carbonic  acid. 
While  leaves,  therefore,  purify  the  air  we  breathe,  flowers  con- 
taminate it ;  though,  of  course,  only  to  a  degree  which  is  relatively 
and  absolutely  insignificant. 

372.  Evolution  of  Heat.  When  carbon  is  consumed  as  fuel,  and 
by  the  oxygen  of  the  air  converted  into  carbonic  acid,  an  amount  of 
heat  is  evolved,  directly  proportionate  to  the  quantity  of  carbon  con- 
sumed, or  of  carbonic  acid  produced.  Precisely  the  same  amount 
is  more  slowly  generated  during  the  gradual  decomposition  of  the 


212  FLOWERING  AND    ITS    CONSEQUENCES. 

same  quantity  of  vegetable  matter  by  decay,  —  a  heat  which  is 
employed  by  the  gardener  when  he  makes  hot-beds  of  tan,  decay- 
ing leaves,  and  manure,  —  or  by  the  breathing  of  animals,  where 
it  maintains  their  elevated  temperature  (364).  The  consumption 
of  a  given  amount  of  carbon  and  hydrogen,  under  whatever  form, 
and  whether  slowly  or  rapidly,  generates  in  all  cases  the  very  same 
amount  of  heat.  Now,  since  flowers  consume  carbon  and  produce 
carbonic  acid,  acting  in  this  respect  like  animals,  they  ought  to 
evolve  heat  in  proportion  to  that  consumption.  This,  in  fact,  they 
do.  The  evolution  of  heat  in  blossoming  was  first  observed  by 
Lamarck,  about  seventy  years  ago,  in  the  European  Arum,  which, 
just  as  the  flowers  open,  "  grows  hot,"  as  Lamarck  stated,  "  as  if 
it  were  about  to  burn."  It  was  afterwards  shown  by  Saussure  in 
a  number  of  flowers,  such  as  those  of  the  Bignonia,  Gourd,  and 
Tuberose,  and  the  heat  was  shown  to  be  in  direct  proportion  to  the 
consumption  of  the  oxygen  of  the  air,  or  in  other  words,  of  the 
carbon  of  the  plant.  The  increase  of  temperature,  in  these  cases, 
was  measured  by  common  instruments.  But  now  that  thermo- 
electric apparatus  affords  the  means  of  measuring  variations  inap- 
preciable by  the  most  delicate  thermometer,  the  heat  generated  by 
an  ordinary  cluster  of  blossoms  may  be  detected.  The  phenome- 
non is  most  striking  in  the  case  of  some  large  tropical  Aroideous 
plants,  where  an  immense  number  of  blossoms  are  crowded  to- 
gether and  muffled  by  a  kind  of  hood,  or  spathe  (390),  which  con- 
fines and  reverberates  the  heat.  In  some  of  these,  the  temperature 
rises  at  times  to  twenty  or  even  fifty  degrees  (Fahrenheit)  above 
that  of  the  surrounding  air.* 

373.  The  source  of  the  heat  in  flowering  is  therefore  evident. 
As  to  its  object,  we  cannot  say  whether  its  production  is  the  imme- 
diate end  in  view,  and  the  plant  burns  some  of  its  carbon  merely 

*  This  increase  of  temperature  occurs  daily  from  the  time  the  flowers  open 
until  they  fade,  but  is  most  striking  during  the  shedding  of  the  pollen.  At 
night,  the  temperature  falls  nearly  to  that  of  the  surrounding  air;  but  in  the 
course  of  the  morning  the  heat  comes  on,  as  it  were,  like  a  paroxysm  of  fever, 
attaining  the  maximum,  day  after  day,  very  nearly  at  the  same  hour  of  the 
afternoon,  and  gradually  declining  towards  evening.  In  ordinary  cases,  the 
heat  of  flowering  is  absorbed  by  the  vaporization  of  the  sap  and  the  exhala- 
tion of  oxygen  by  the  foliage  (besides,  a  large  amount  is  absorbed  from  the 
solar  radiation  and  rendered  latent  in  the  process  of  assimilation) ;  so  that  the 
actual  temperature  of  a  leafy  plant  in  summer  is  lower  than  that  of  the  atmos- 
phere. 


THE  EEPOSE  OF  PLANTS.  213 

as  fuel,  or  whether  the  evolution  of  heat  and  the  formation  of  car- 
bonic acid  are  incidental  consequences  of  certain  necessary  trans- 
formations. We  have  remarked  that  the  principal  consumption 
takes  place  in  the  flower ;  and  that  a  store  is  laid  up  in  the  fruit 
and  seed.  But  much  even  of  this  is  consumed,  with  the  evolution 
of  heat,  when  the  seed  germinates.  By  a  not  very  violent  met- 
aphor it  may  be  said,  therefore,  that  in  the  Century-plant  (369), 
which,  after  living  a  hundred  years,  consumes  itself  in  producing 
and  giving  life  to  its  off*spring,  who  literally  rise  from  its  ashes,  we 
have  the  realization  of  the  fabled  Phcenix  ! 

374.  Plants  need  a  Season  of  Rest.  There  is  another  condition, 
which,  if  not  essential  to  the  production  of  flowers,  exerts  an  im- 
portant influence.  When  plants  are  in  continual  and  luxuriant 
growth,  rapidly  pushing  forth  leafy  branches,  they  are  not  apt  to 
produce  flower-buds.  Our  fruit-trees,  in  very  moist  seasons,  or 
when  cultivated  in  too  rich  a  soil,  often  grow  luxuriantly,  but  do 
not  flower.  The  same  thing  is  observed  when  our  Northern  fruit- 
trees  are  transported  into  tropical  climates.  On  the  other  hand, 
whatever  checks  this  continuous  growth,  without  aflecting  the 
health  of  the  individual,  causes  blossoms  to  appear  earlier  and 
more  abundantly  than  they  otherwise  would.  It  is  for  this  rea- 
son that  transplanted  fruit-trees  incline  to  flower  the  first  season 
after  their  removal,  though  they  may  not  blossom  again  for  several 
years.  A  season  of  comparative  rest  is  essential  to  the  transfor- 
mation by  which  flowers  are  formed.  It  is  in  autumn,  or  at  least 
after  the  vigorous  vegetation  of  the  season  is  over,  that  our  trees 
and  shrubs,  and  most  perennial  herbs,  produce  the  flower-buds  of 
the  ensuing  year. 

375.  The  requisite  annual  season  of  repose,  which  in  temperate 
climes  is  attained  by  the  lowering  of  the  temperature  in  autumn 
and  winter,  is  scarcely  less  marked  in  many  tropical  countries, 
where  winter  is  unknown.  But  the  result  is  brought  about,  in  the 
latter  case,  not  by  cold,  but  by  excessive  heat  and  dryness.  The 
Cape  of  Good  Hope,  the  Canary  Islands,  and  the  southern  part 
of  California,  may  be  taken  as  illustrations.  In  the  Canaries,  the 
growing  season  is  from  November  to  March,  —  the  winter  of  the 
northern  hemisphere,  —  their  winter  also,  as  it  is  the  coolest  sea- 
son, the  mean  temperature  being  66°  Fahr.  But  the  rains  fall  reg- 
ularly and  vegetation  is  active  ;  while  in  summer,  from  April  to 
October,  it  very  seldom  rains,  and  the  mean  temperature  is  as  high 


214  FLOWERING    AND    ITS    CONSEQUENCES. 

as  73°.  During  this  dry  season,  when  the  scorching  sun  reduces 
the  soil  nearly  to  the  dryness  and  consistence  of  brick,  ordinary 
vegetation  almost  completely  disappears ;  and  the  Fig-Marigolds, 
Euphorbias,  and  other  succulent  plants,  which,  fitted  to  this  condi- 
tion of  things,  alone  remain  green,  not  unaptly  represent  the  Firs 
and  other  evergreens  of  high  northern  latitudes.  The  dry  heat 
there  brings  about  the  same  state  of  vegetable  repose  as  cold  with 
us.  The  roots  and  bulbs  then  lie  dormant  beneath  the  sun-burnt 
crust,  just  as  they  do  in  our  frozen  soil.  When  the  rainy  season 
sets  in,  and  the  crust  is  softened  by  moisture,  they  are  excited  into 
growth  under^a  diminished  temperature,  just  as  with  us  by  heat; 
and  the  ready-formed  flower-buds  are  suddenly  developed,  cloth- 
ing at  once  the  arid  waste  with  a  profusion  of  blossoms.  The 
vegetation  of  such  regions  consists  mainly  of  succulents,  which  are 
able  to  live  through  the  drought  and  exposure  ;  of  bulbous  plants, 
which  run  through  their  course  before  the  drought  becomes  severe, 
then  lose  their  foliage,  while  the  bulb  remains  quiescent,  safely 
protected  under  ground  until  the  rainy  season  returns  ;  and  of  an- 
nuals, which  make  their  whole  growth  in  a  few  weeks,  and  ripen 
their  seeds,  in  which  state  the  species  securely  passes  the  arid  sea- 
son. A  season  of  interruption  to  growth,  produced  either  by  cold 
or  dryness,  occurs,  in  a  more  or  less  marked  degree,  through  every 
part  of  the  world. 

376.  These  considerations  explain  the  process  o^ forcing  plants, 
and  other  operations  of  horticulture,  by  which  we  are  enabled 
to  obtain  in  winter  the  flowers  and  fruits  of  summer.  The  gar- 
dener accomplishes  these  results  principally  by  skilful  alterations 
of  the  natural  period  of  repose.  He  gives  the  plant  an  artifi- 
cial period  of  rest  by  dryness  at  the  season  when  he  cannot  com- 
mand cold,  and  then,  by  the  influence  of  heat,  light,  and  moisture, 
which  he  can  always  command,  causes  it  to  grow  at  a  season 
when  it  would  have  been  quiescent.  Thus  he  retards  or  advances, 
at  will,  the  periods  of  flowering  and  of  rest,  or  in  time  completely 
inverts  them. 


THE    INFLORESCENCE.  215 

CHAPTER    YIII. 

OF    THE    INFLORESCENCE. 

377.  Inflorescence  is  the  term  used  to  designate  the  arrangement 
of  flowers  upon  the  stem  or  branch.  The  flower,  like  the  branch, 
is  evolved  from  a  bud.  Flower-buds  and  leaf-buds  are  often  so 
similar  in  appearance,  that  it  is  difficult  to  distinguish  one  from  the 
other  before  their  expansion.  The  most  conspicuous  parts  of  the 
flower  are  so  obviously  analogous  to  the  leaves  of  a  branch,  that 
they  are  called  in  common  language  the  leaves  of  the  flower. 
Such  a  flower  as  the  double  Camellia  appears  as  if  composed  of  a 
rosette  of  white  or  colored  leaves,  resembling,  except  in  their  color 
and  greater  delicacy,  the  clusters  of  leaves  which  crown  the  offsets 
of  such  plants  as  the  Houseleek  (Fig.  174),  &c.  We  may  therefore 
naturally  consider  a  ffower-bud  as  analogous  to  a  leaf-bud ;  and 
a  flower,  consequently,  as  analogous  to  a  short  leafy  branch. 

378.  This  analogy  is  confirmed  by  the  position  which  flowers 
occupy.  Whatever  views  may  be  entertained  respecting  the  na- 
ture of  flowers,  it  is  certain  that  they  appear  at  the  same  situations 
as  ordinary  buds,  and  at  no  other.  They  have  the  same  relation 
to  the  stem  or  flower-stalk  which  bears  them,  that  leaf-buds  have 
to  the  stem  or  branch  from  which  they  arise  ;  that  is,  they  occupy 
the  extremity  of  the  stem  or  branch,  and  the  axil  of  the  leaves 
(144,  148).  Consequently,  the  arrangement  of  the  buds  governs 
the  whole  arrangement  of  the  blossoms,  as  well  as  that  of  the 
branches.  The  flower-stalk  is  merely  the  last  term  of  ramifica- 
tion. The  almost  endless  variety  of  modes  in  which  flowers  are 
clustered  upon  the  stem,  many  of  them  exhibiting  the  most  grace- 
ful of  natural  forms,  all  implicitly  follow  the  general  law  which 
has  controlled  the  whole  development  of  the  vegetable  from  the 
beginning.  We  have,  throughout,  merely  buds  terminating  the 
stem  and  branches,  and  buds  from  the  axil  of  the  leaves. 

379.  The  simplest  kind  of  inflorescence  is,  of  course,  that  of  a 
solitary  flower,  —  a  single  flower-stalk  bearing  a  single  flower  ;  as 
in  Fig.  249  and  Fig.  229.  The  naked  stalk  which  supports  the 
flower  is  termed  the  Peduncle.  If  the  flower  is  not  raised  on  a 
proper  stalk,  it  is  said  to  be  sessile. 


216  THE    INFLORESCENCE. 

380.  In  both  of  the  examples  just  adduced,  the  flower  is  solita- 
ry;  but  there  is  a  difl^erence  in  one  respect.  In  Fig.  249,  the 
flower  terminates  the  stem  ;  it  stands  in  the  place  of  a  terminal 
bud.  In  Fig.  229,  it  arises  from  the  axil  of  a  leaf,  or  represents 
an  axillary  bud.  These  two  cases,  in  fact,  exhibit  the  two  types 
(reduced  to  the  greatest  simplicity),  to  the  one  or  the  other  of 
which  all  the  forms  of  inflorescence  belong. 

381.  We  may  begin  with  the  second  of  these  plans ;  in  which 
the  flowers  all  spring  from  axillary  buds ;  while  the  terminal  bud, 
developing  as  an  ordinary  branch,  continues  the  stem  or  axis  in- 
definitely. For  the  stem  in  such  case  may  continue  to  elongate, 
and  produce  a  flower  in  the  axil  of  every  leaf,  until  its  powers  are 
exhausted  (Fig.  230).     This  gives  rise,  therefore,  to  what  is  called 

382.  Indefinite  or  Indeterminate  Inflorescence.  The  primary  axis  is 
here  never  terminated  by  a  flower;  but  the  secondary  axes  (from 
axillary  buds)  are  thus  terminated.  Before  we  enumerate  the  va- 
rious forms  of  inflorescence  of  this  class,  a  few  terms  must  be  de- 
fined which  necessarily  come  into  use  in  distinguishing  the  parts  of 
a  flower-cluster.  ^  The  primary  axis,  or  general  stalk  which  bears 
the  whole  cluster  of  flowers,  retains  the  name  of  Peduncle  (379), 
while  the  secondary  axes,  which  form  the  partial  flower-stalks  and 
support  each  a  single  blossom,  now  receive  the  name  of  Pedicels. 
These,  being  axillary  branches,  must  of  course  be  subtended  each 
by  a  leaf,  or  else  will  show  the  scar  left  by  its  fall.  The  leaves  of 
an  inflorescence,  however,  are  usually  reduced  in  size,  or  changed 
in  appearance,  so  as  to  be  quite  unlike  the  ordinary  leaves  of  the 
plant :  they  are  called  sometimes  floral  leaves,  or  more  commonly 
Bracts.  The  bracts  are  often  reduced  to  a  minute  size,  so  as  to 
escape  ordinary  notice  :  they  very  frequently  fall  off"  when  the 
flower-bud  in  their  axil  expands,  or  even  still  earlier ;  and  some- 
times, as  in  the  greater  part  of  the  Mustard  Family,  they  altogether 
fail  to  appear.  The  portion  of  the  general  stalk  along  which 
flowers  are  borne  is  called  the  axis  of  the  inflorescence,  and  some- 
times, especially  when  covered  with  sessile  flowers,  the  Rachis 
(from  its  resemblance  or  analogy  to  the  backbone). 

383.  The  various  forms  of  indefinite  inflorescence  which  in  de- 
scriptive botany  are  distinguished  by  special  names,  as  might  be 
expected,  run  into  one  another  through  endless  intermediate  gra- 
dations. In  nature,  they  are  not  so  absolutely  fixed  as  in  our  writ- 
ten definitions  ;  and  whether  this  or  that  name  should  be  used  in  a 


INDETERMINATE  INFLORESCENCE. 


217 


particular  case  is  often  a  matter  of  fancy.  The  subjoined  account 
of  the  principal  kinds  will  at  the  same  time  bring  to  view  the  con- 
nection between  them. 

384.  A  Raceme  is  formed  when  the  primary  axis  continues  to 
lengthen,  and  the  flowers  singly  produced  from  the  axil  of  each 
bract  are  supported  on  pedicels  of  their  own,  as  in  Fig.  230,  235. 
The  flowers  and  fruit  of  the  Currant,  Barberry,  and  wild  Black 
Cherry  (Fig.  236)  furnish  most  familiar  examples.  The- lowest 
flowers  of  a  raceme,  being  evidently  the  oldest,  are  the  first  to  ex- 
pand, and  the  others  follow  in  regular  succession,  from  the  base  to 
the  summit.  Indeed,  the  lower  flowers  often  produce,  or  (as  in 
the  Snowberry,  Symphoricarpus  racemosus)  even  ripen,  their 
fruit,  before  the  summit  has  ceased  to  grow  and  develope  new 
flowers. 


385.  A  Corpib  (Fig.  231,  239)  is  the  same  as  a  raceme,  except 
that  the  lower  pedicels  are  elongated,  so  as  to  form  a  level-topped 
or  slightly  convex  bunch  of  flowers  ;  as  in  the  Hawthorn,  &c. 

386.  An  Umbel  (Fig.  232)  differs  from  a  corymb  only  in  having 
all  the  pedicels  arising  from  the  same  apparent  point ;  the  general 
peduncle,  in  this  case,  bearing  several  flowers  without  any  percep- 
tible elongation  of  the  internodes  of  the  axis  of  inflorescence.  The 
Primrose  and  the  Milkweed  afford  familiar  examples  of  the  simple 
umbel. 

387.  A  corymb  being  evidently  the  same  as  a  raceme  with  a 
short  main  axis,  and  an  umbel  the  same  as  a  corymb  with  a  still 
shorter  axis,  it  is  evident  that  the  outer  flowers  of  an  umbel  or 
corymb  correspond  to  the  lowermest  in  the  raceme,  and  that  these 
will  first  expand,  the  blossoming  proceeding  regularly  from  the 
base  to  the  apex,  or  (which  is  the  same  thing)  from  the  circumfer- 

FIG.  230-232.    Diagrams  of  a  simple  raceme,  corymb,  and  umbel. 

19 


^18 


THE    INFLORESCENCE. 


ence  to  the  centre.  This  mode  of  development  uniformly  takes 
place  when  the  flowers  arise  from  axillary  buds ;  on 
which  account  the  indefinite  mode  of  inflorescence  is 
also  called  the  centripetal. 

388.  In  all  the  foregoing  cases,  the  flowers  are  raised 
on  stalks,  or  pedicels.  When  these  are  wanting,  or 
very  short,  the  spike  or  the  head  is  produced. 

389.  A  Spike  is  the  same  as  the  raceme,  except  that 
the  flowers  are  sessile,  or  destitute  of  any  apparent  pedi- 
cels ;  as  in  the  Plantain  (Fig.  233).  It  is  an  indetermi- 
nate or  centripetal  inflorescence,  with  the  primary  axis 
elongated,  and  the  secondary  axes  not  at  all  elongated, 
but  terminated  at  their  very  origin  by  a  flower.  Two 
varieties  of  the  spike  have  received  independent  names, 
viz.  the  Spadix  and  the  Ament. 

390.  A  Spadix  is  a  fleshy  spike  enveloped  by  a  large 
*^            bract  or  modified  leaf,  called  a  Spathe,  as  in  Calla  pa- 

lustris  (Fig.  234),  the  cultivated  Calla  iEthiopica,  Arum  triphyllum, 
or  Indian  Turnip  (Fig.  235),  and  the  Skunk  Cabbage  (see  Araceae). 


391.  An  Ament,  or  Catkin,  is  merely  that  kind  of  spike  with  scaly 

FIG.  233.    Young  spike  of  Plantago  major. 

FIG.  234-239.    Forms  of  inflorescence.    234,  235.  Spadix  of  Calla  and  of  Arum,  with  the 
spalhe.    236.  A  raceme.    237.  A  cyme.    233.  A  panicle.    239.  A  corymb. 


INDETERMINATE    INFLORESCENCE. 


219 


bracts  borne  by  the  Birch,  Poplar,  Willow,  and,  as  to  one  of  the 
two  sorts  of  flowers,  by  the  Oak,  Walnut,  and  Hickory,  which  are 
accordingly  called  amentaceous  trees.  Calkins  usually  fall  off*  in 
one  piece,  after  flowering  or  fruiting,  especially  the  sterile  cat- 
kins. 

392.  The  Head,  or  Capitulum,  is  a  globular  cluster  of  sessile  flow- 
ers, like  that  of  the  Button  Bush,  the  balls  of  the  Buttonwood  or 
Plane-tree,  &c.  It  is  a  many-flowered  centripetal  inflorescence, 
in  which  neither  the  primary  axis  nor  the  secondary  axes  are  at  all 
lengthened.  We  may  conceive  it  to  originate,  either  from  the 
non-development  of  the  pedicels  of  an  umbel  (Fig.  232),  or  the 
non-elongation  of  the  axis  of  a  spike.  In  other  words,  the  head 
differs  from  a  spike  only  in  its  shortness.  So  what  is  at  first  a 
head  frequently  elongates  into  a  spike  as  it  grows  older  ;  as  in 
many  species  of  Clover,  &c.  In  all  these  forms,  the  blossoms  ne- 
cessarily expand  from  the  base  to  the  apex,  or  from  the  circum- 
ference to  the  centre  (387). 

393.  The  base  both  of  the  head  and  the  umbel  is  frequently 
furnished  with  a  number  of  imper- 
fect leaves  or  bracts,  crowded  to- 
gether, or  forming  a  whorl  (236, 
Fig.  232),  termed  an  Involucre. 
The  involucre  assumes  a  great  va- 
riety of  forms  ;  sometimes  resem- 
bling a  calyx ;  and  sometimes  (as 
in  Cornus  Florida,  or  the  common 
Dogwood,  and  C.  Canadensis,  Fig. 
240),  becoming  petal-like,  and 
much  more  showy  than  the  blos- 
som itself.  It  is,  however,  distin- 
guished from  the  calyx  or  corolla 
by  including  a  number  of  flowers. 
Sometimes,  however,  as  in  the 
Mallow  Family  and  Hibiscus,  the 
involucre  forms  a  kind  of  outer 
calyx  to  each  flower. 

394.  The  axis,  or  rachis  (382),  of  a  head  is  called  the  Recepta- 
Frequently,  instead   of  being   globular  or  somewhat  pro- 


CLE. 


FIG.  240.    Cornus  Canadensis;  with  its  petal-like  four-leaved  involucre  surrounding  ahead 
of  flowers :  a,  a  separate  flower  from  the  head,  enlarged. 


220 


THE   INFLORESCENCE. 


longed,  it  is  flat  or  depressed,  and  dilated  horizontally,  so  as  to 
allow  a  large  number  of  flowers  to  stand  on  its  level  or  merely 
convex  surface  ;  as  in  the  Sunflower,  and  in  similar  plants.  What 
were  called  compound  flowers  by  the  older  botanists,  such  as  the 
Sunflower,  Aster,  Marigold,  &c.,  are  heads  of  this  kind,  containing 
a  smaller  or  larger  number  of  flowers,  crowded  together  on  the 
receptacle  (or  dilated  branch),  and  surrounded  by  an  involucre. 
Not  unfrequently  the  separate  flowers  are  also  subtended  by  bracts  ; 
as  in  the  Sunflower,  Rudbeckia,  Coreopsis,  &c.,  when  these  re- 
ceive the  name  of  Pale^,  or  Chaff.     (See  Ord.  Compositse.) 

395.  The  Fig  presents  a  case  of  very  singular  inflorescence 
(Fig.  241,  242),  where  the  flowers  apparently  occupy  the  inside 
instead  of  the  outside  of  the  axis,  being  inclosed  within  the  fleshy 
receptacle,  which  is  hollow  and  nearly  closed  at  the  top.  The  mag- 
nified slice  (Fig.  243)  shows  that  the  inner  surface  is  lined,  not 
with  mere  seeds,  as  is  commonly  supposed,  but  with  a  multitude 
of  small  blossoms.  The^^  is  therefore  something  like  a  mulberry 
(Fig.  244),  or  a  pine-apple,  turned  inside  out. 


396.  In  all  the  cases  yet  mentioned,  the  flower-clusters  are  sim- 
ple ;  the  ramification  not  passing  beyond  the  first  step ;  the  lateral 

FIG.  241.    A  Fig.    242.  A  vertical  section.    243.  A  thin  slice  from  the  same,  magnified. 
FIG.  244.    The  Mulberry  in  fruit.    245.  One  of  the  component  flowers,  magnified.    246.  One 
of  the  flowers  with  a  section  of  the  juicy  floral  envelopes. 


INDETERMINATE  INFLORESCENCE. 


221 


buds  being  at  once  terminated  by  a  single  flower.  But  the  lateral 
flower-stalks  may  themselves  branch,  just  as  ordinary  branches 
give  rise  to  branchlets ;  when  the  inflorescence  becomes  compound. 
The  modifications  produced  by  a  second  branching  of  the  inflores- 
cence are  readily  understood.  If  the  branches  of  a  raceme  are 
prolonged,  and  bear  other  flowers  on  pedicels  similarly  arranged,  a 
compound  raceme  is  produced  ;  or,  if  the  flowers  are  sessile,  a  com- 
pound  spike  is  formed.  A  corymb,  the  branches  of  which  are 
similarly  divided,  forms  a  com- 
pound corymb ;  and  an  umbel, 
where  the  branches  (often  called 
rays)  bear  smaller  umbels  at  their 
apex,  is  termed  a  compound  um- 
bel ;  examples  of  which  occur 
in  almost  all  the  species  of  the 
Family  Umbelliferse,  which  is 
so  named  because  all  its  plants 
bear  umbels.  For  these  sec- 
ondary umbels,  a  good    English 

name  has  been  employed  by  Dr.  Darlington,  that  of  Umbellets. 
Their  involucre,  when  they  have  any,  is  distinguished  from  that  of 
the  principal  umbel  by  the  name  of  Involucel. 

397.  It  is  often  necessary  to  distinguish  between  the  bracts  on 
the  branches  of  the  inflorescence,  and  those  at  the  base  of  the  pri- 
mary branches  ;  in  which  case  the  former  are  termed  Bracteoles, 
or  Bractlets  ;  but  there  is  no  real  limit,  either  between  bractlets 
and  true  bracts,  or  between  bracts  and  true  leaves. 

398.  When  the  inflorescence  is  compound,  it  is  readily  seen  that 
two  or  more  modes  of  inflorescence  may  be  combined ;  the  first 
ramification  following  one  plan,  and  the  subdivision  another.  The 
combination  is  usually  expressed  by  a  descriptive  phrase,  as  "  spikes 
racemose,  or  racemed,"  "  heads  corymbose,"  &c.  The  combina- 
tion of  the  raceme  and  the  corymb  or  the  cyme  gives  rise  to  a 
form  of  inflorescence  which  has  a  technical  name,  viz. :  — 

399.  The  Panicle.  This  is  formed  when  the  secondary  axes  of  a 
raceme  branch  in  a  corymbose  manner,  as  in  numerous  Grasses 
(Fig.  238),  or  those  of  a  corymb  divide  in  the  manner  of  a  ra- 
ceme.    And  the  name  is  loosely  applied  to  almost  any  open  and 

FIG.  247.  Compound  umbel  (in  fruit)  of  Osmorhiza  longistylis :  a,  the  involucre:  b,  b,  in- 
volucela,    248.  A  separate  flower  enlarged,  with  its  subtending  bract  of  the  involucel. 

19* 


222 


THE    INFLORESCENCE. 


more  or  less  elongated  inflorescence  which  is  irregularly  branched 
twice,  thrice,  or  a  greater  number  of  times. 

400.  A  Thyrsus  is  merely  a  compact  panicle  of  a  pyramidal,  oval, 
or  oblong  outline  ;  such  as  the  cluster  of  flowers  of  the  Lilac  and 
Horsechestnut,  a  bunch  of  grapes,  &c. 

401.  Definite  or  Determinate  Inflorescence.  In  this  class,  the  flow- 
ers all  represent  tecminal  buds  (380).  The  primary  axis  is  direct- 
ly terminated  by  a  single  flower-bud,  as  in  Fig.  249,  and  its  growth 
is  of  course  arrested,  as  it  is  now  incapable  of  any  further  elonga- 
tion. In  this  way  we  have  a  solitary  terminal  flower.  Further 
growth  can  take  place  only  by  the  development  of  secondary  axes 
from  axillary  buds.  These  may  develope  at  once  as  peduncles,  or 
as  leafy  branches ;  but  they  are  in  either  case  arrested,  after  more 
or  less  elongation,  by  a  flower-bud,  just  as  the  primary  axis  was 
(Fig.  250).  If  further  development  ensues,  it  is  by  the  production 
of  branches  of  the  third  order,  from  the  axils  of  leaves  or  bracts  on 
the  branches  of  the  second  order  (Fig.  251)  ;  and  so  on.  Hence 
this  mode  of  inflorescence  is  said  to  be  definite  or  determinate,  in 
contradistinction  to  the  indeterminate  mode,  already  treated  of 
(382,  &c.),  where  the  primary  or  leading  axes  elongate  indefi- 
nitely, or  merely  cease  to  grow  from  the  failure  of  nourishment,  or 
some  other  extrinsic  cause.  The  most  common  and  most  regular 
cases  of  determinate  inflorescence  occur  in  opposite-leaved  plants, 
for  obvious  reasons  ;  and  such  are  accordingly  chosen  for  the  sub- 
joined illustrations.  But  the  Rose,  Potentilla,  and  Buttercup  fur- 
nishf  familiar  examples  of  the  kind  in  alternate-leaved  plants. 


402.  The  determinate  mode  of  inflorescence  assumes  forms 
which  closely  imitate  the  various  forms  of  the  indeterminate  kind, 
already  described,  with  which  they  have  been  confounded,  and 


FIG.  249-251.    Diagrams  of  regular  forms  of  determinate  or  centrifugal  inflorescence. 


DETERMINATE  INFLORESCENCE.  223 

on  this  account  have  failed  to  receive  distinctive  names.  When, 
for  example,  all  the  secondary  axes  connected  with  the  inflores- 
cence are  arrested  by  terminal  flowers  without  any 
onward  growth  except  what  forms  their  footstalks  or 
pedicels,  and  these  are  nearly  equal  in  length,  a  ra- 
ceme-like inflorescence  is  produced,  as  in  Fig.  252. 
When  the  flowers  are  developed  in  this  way,  with 
scarcely  any  pedicels,  the  spike  is  imitated.  These 
are  essentially  distinguished  from  the  true  raceme  and 
spike,  however,  by  the  reverse  order  of  development 
of  the  blossoms  ;  the  terminal  and  then  the  upper  ones 
opening  earliest,  and  the  others  expanding  in  succes- 
sion from  above  downwards  ;  while  the  blossoming  of 
the  raceme  proceeds  from  below  upwards.  Or  when, 
by  the  elongation  of  the  lower  secondary  axes,  a  cor- 
ymb is  imitated,  the  flowers  are  found  to  expand  in 
succession  from  the  centre  towards  the  circumference  of  the  flat- 
topped  cluster,  while  the  contrary  occurs  in  the  corymb.  That  is, 
while  the  order  in  indeterminate  inflorescence  is  centripetal  (387), 
that  of  the  determinate  mode  is  centrifugal.  When  the  determi- 
nate inflorescence  assumes  the  corymbose  form,  which  it  more 
commonly  does,  it  has  a  distinctive  name,  viz. :  — 

403.  The  Cyme.  This  is  a  flat-topped,  rounded  or  expanded  in- 
florescence, whether  simple  or  compound,  of  the  determinate  class  ; 
of  which  those  of  the  Laurustinus,  Elder,  Dogwood,  and  Hydran- 
gea are  fully  developed  and  characteristic  examples.  More  com- 
monly it  is  from  the  upper  axils  alone  that  the  flower-bearing 
branches  successively  proceed,  as  indicated  in  Fig.  249-251.  In 
more  compound  and  compact  cymes  (Fig.  237),  such  as  those  of 
the  Laurustinus,  Dogwood,  &c.,  the  leaves  or  bracts  are  usually 
minute,  rudimentary,  or  abortive,  and  all  the  numerous  flower-buds 
of  the  cluster  are  fully  formed  before  any  of  them  expand ;  and 
the  blossoming  then  runs  through  the  whole  cluster  in  a  short  time, 
commencing  in  the  centre  of  the  cyme,  and  then  in  the  centre  of 
each  of  its  branches,  or  Cymules,  and  thence  proceeding  centrifu- 
gally.  But  in  the  Chickweeds  (Fig.  253),  in  Hypericum,  and 
many  such  like  plants,  the  successive  production  of  the  branches 
and  the  evolution  of  the  flowers,  beginning  with  that  which  ar- 
rests the  growth  of  the  primary  axis,  go  on  gradually  through  the 

FIG.  252.     Definite  inflorescence  imitating  a  raceme. 


224  THE    INFLORESCENCE. 

whole  summer,  until  the  powers  of  the  plant  are  exhausted,  or 
until  all  the  branchlets  or  peduncles  are  reduced  to  single  inter- 
nodes,  or  pedicels  without  any  leaves,  bracts,  or  bractlets,  when 
no  further  development  can  take  place.  Such  cases  enable  us  to 
study  the  determinate  inflorescence  to  advantage,  and  to  follow  the 
successive  steps  of  the  ramification  by  direct  observation. 


404.  The  FfSCicle  is  a  densely  crowded  cyme,  with  the  flowers 
almost  sessile,  or  on  short  peduncles  of  nearly  equal  length  ;  as  in 
the  Sweet  William. 

405.  A  Glomerule  is  a  cyme  condensed  into  a  head  or  short  spike. 
It  is  to  the  cyme  what  the  capitulum  is  to  the  corymb  or  umbel. 

406.  There  are  several  abnormal  modifications  of  inflorescence, 
especially  of  the  determinate  or  centrifugal  kind,  arising  from  ir- 
regular development,  or  the  suppression  of  parts,  such  as  the  non- 
appearance sometimes  of  the  central  flower,  or  often  of  one  of  the 
lateral  branches  at  each  division ;  as  in  the  ultimate  ramifications 
of  Fig.  253,  where  one  of  the  lateral  pedicels  is  wanting.  When 
this  deviation  is  completely  carried  out,  that  is,  when  one  of  the 
side  branches  regularly  fails  to  appear,  the  cyme  is  apparently 
converted  into  a  kind  of  one-sided  raceme,  and  the  flowers  seem 
to  expand  from  below  upwards,  or  centripetally.  The  diagram. 
Fig.  254,  when  compared  with  Fig.  253,  explains  this  anomaly. 
The  place  of  the  axillary  branch  which  fails  to  develope  at  each 
ramification  is  indicated  by  the  dotted  lines.  Cases  like  this  occur 
in  several  Hypericums,  and  in  some  other  opposite-leaved  plants. 
An  analogous  case  occurs  in  many  alternate-leaved  plants ;  where 
the  stem,  being  terminated  by  a  flower,  is  continued  by  a  branch 
from  the  axil  of  the  uppermost  leaf  or  bract :  this,  bearing  a  flow- 

FIG.  253.    The  open,  progressively  developed  cyme  of  Arenaria  stricta. 


ABNORMAL    INFLORESCENCE. 


225 


er,  is  similarly  prolonged  by  a  secondary  branch,  that  by  a  third, 
and  so  on  ;  as  is  shown  in  the 
diagram,  Fig.  255.  Such 
forms  of  inflorescence,  which 
we  may  observe  in  Drosera, 
and  in  most  Sedums  and  Bo- 
raginacese,  imitate  the  raceme 
so  nearly  that  they  have  com- 
monly been  considered  as  of 
that  kind.  They  are  distin- 
guishable, however,  by  the 
position  of  the  flowers  opposite  254  255 

the  leaf  or  bract,  or  at  least 

out  of  its  axil ;  while  in  the  raceme,  and  in  every  modification  of 
centripetal  inflorescence,  the  flowers  necessarily  spring  from  the 
axils  of  the  bracts.  But  if  the  bracts  disappear,  as  they  commonly 
do  in  the  Forget-me-not,  &c.,  the  true  nature  of  the  inflorescence 
is  not  readily  made  out.  The  undeveloped  summit  is  usually 
coiled  in  a  spiral  or  circinate  (257)  manner,  gradually  unrolling 
as  the  flowers  grow  and  expand,  and  becoming  straight  in  fruit. 
On  account  of  this  coiled  arrangement,  such  cymes  or  false  ra- 
cemes are  said  to  be  helicoid,  or  scorpioid. 

407.  The  cyme,  raceme,  head,  &c.,  as  well  as  the  one-flowered 
peduncle,  may  be  produced,  either  at  the  extremity  of  the  stem  or 
leafy  branch  (terminal)^  or  in  the  axil  of  the  leaves  (axillary). 
The  case  of  a  peduncle  opposite  a  leaf,  as  in  the  Poke  (see  Ord. 
Phytolaccacese),  the  Grape-vine,  &c.,  is  just  that  illustrated  in  Fig. 
255,  except  that  in  these  cases  the  peduncles  bear  a  cluster  of  flow- 
ers instead  of  a  single  one.  The  tendrils  of  the  vine  (Fig.  134) 
occupy  the  same  position,  and  are  of  the  same  nature,  so  that  they 
are  not  incorrectly  said  to  be  sterile  and  modified  peduncles.  In 
a  growing  Grape-vine,  it  is  plain  to  see  that  the  uppermost  tendril 
really  terminates  the  stem  ;  and  that  the  latter  is  continued  by  the 
growth  of  the  axillary  bud  situated  between  the  petiole  and  the 
peduncle ;  the  branch  thus  formed,  assuming  the  same  direction 
as  the  main  stem,  and  appearing  to  be  its  prolongation,  throws  the 
peduncle  or  tendril  to  the  side  opposite  the  leaf. 

408.  The  extra-axillary  peduncles  of  most  species  of  Solanum 
are  to  be  similarly  explained.     They  are  really  terminal  pedun- 

FIG.  254,  255.    Plan  of  two  modifications  of  helicoid  cymes  or  false  racemes. 


22^  THE    INFLOEESCENCE. 

cles,  which  have  become  lateral  by  the  evolution  of  a  branch  from 
an  axil  below,  which  takes  the  direction  of  the  main  stem,  so  as 
to  form  an  apparent  continuation  of  it.  This  has  been  explained 
on  the  supposition  of  the  cohesion  of  the  base  of  an  axillary  pedun- 
cle with  the  stem ;  which  could  well  apply  only  to  those  cases 
where  the  peduncle  is  in  the  same  vertical  line  as  the  leaf  beneath. 
Such  peduncles  may  sometimes  come  from  extra-axillary  acces- 
sory buds,  such  as  those  shown  in  Fig.  133. 

409.  In  the  Linden  (see  Ord.  Tiliacese)  the  peduncle  appears  to 
spring  from  the  middle  of  a  peculiar  foliaceous  bract.  But  this  is 
rather  a  bractlet,  inserted  on  the  middle  of  the  peduncle,  and  de- 
current  down  to  its  base,  just  as  many  leaves  are  decurrent  on  the 
stem  (298)  in  Thistles,  &c. 

410.  A  peduncle  which  arises  from  the  stem  at  or  beneath  the 
surface  of  the  ground,  as  in  the  Primrose,  the  Daisy,  the  so-called 
stemless  Violets,  &c.,  is  called  a  radical  peduncle,  or  a  Scape. 

411.  A  combination  of  the  two  classes  of  inflorescence  is  not 
unusual,  the  general  axis  developing  in  one  way,  but  the  separate 
clusters  of  flowers  in  the  other.  Thus  the  heads  of  all  the  Com- 
positse  (such  as  Thistles,  Asters,  &;c.)  are  centripetal,  the  flowers 
expanding  regularly  from  the  margin  or  circumference  to  the  cen- 
tre ;  while  the  branches  that  bear  the  heads  are  developed  in  the 
centrifugal  mode,  the  central  heads  first  coming  into  flower. 

412.  This  is  exactly  reversed  in  all  Labiatoe  (plants  of  the  Mint 
tribe)  ;  where  the  stem  grows  on  indefinitely  in  the  centripetal 
mode,  bearing  axillary  clusters  of  flowers  in  the  form  of  a  general 
raceme  or  spike,  which  blossoms  from  below  upwards ;  while  the 
flowers  of  each  cluster  form  a  cyme,  and  expand  in  the  centrifugal 
manner.  These  cymes,  or  cymules,  of  Labiatse  are  usually  close 
and  compact,  and  being  situated  one  in  each  axil  of  the  opposite 
leaves,  the  two  together  frequently  form  a  cluster  which  surrounds 
the  stem,  like  a  whorl  or  verticil  (as  in  the  Catnip  and  Horehound): 
hence  such  flowers  are  often  said  to  be  whorled  or  verticiUate, 
which  is  not  really  the  case,  as  they  evidently  all  spring  from  the 
axils  of  the  two  leaves.  The  apparent  verticil  of  this  kind  is  some- 
times termed  a  Verticillaster. 

413.  True  whorled  flowers  occur  only  in  some  plants  with 
whorled  leaves,  as  in  Hippuris  and  the  Water  Milfoil. 


THE    FtOWER. 


227 


CHAPTER    IX. 


OF    THE    FLOWER. 


Sect.  I.     Its  Organs,  or  Component  Parts. 

414.  Having  glanced  at  the  circumstances  which  attend'  and 
control  the  production  of  flowers,  and  considered  the  laws  which 
govern  their  arrangennent,  we  have  next  to  inquire  what  the  flower 
is  composed  of. 

415.  The  Flower  (110,  111)  assumes  an  endless  variety  of  forms 
in  different  species,  so  that  it  is  very  difficult  properly  to  define  it. 
The  name  was  earliest  applied,  as  it  is  still  in  popular  language 
generally  applied,  to  the  delicate  and  gayly-colored  leaves  of  petals, 
so  different  from  the  sober  green  of  the  foliage.  But  the  petals, 
and  all  these  bright  hues,  are  entirely  wanting  in  many  flowers, 
while  ordinary  leaves  sometimes  assume  the  brilliant  coloring  of 
the  blossom.  The  stamens  and  pistils  are  the  characteristic  or- 
gans of  the  flower ;  but  sometimes  one  or  the 

other  of  these  disappear  from  a  particular  flow- 
er, and  both  are  absent  from  full  douhle  Roses, 
Camellias,  &c.,  in  which  we  have  only  a  regu- 
lar rosette  of  delicate  leaves.  This,  however, 
is  an  unnatural  state,  the  consequence  of  con- 
tinued cultivation. 

416.  A  complete  Jlower  consists  of  the  essen- 
tial organs  of  reproduction  (viz.  stamens  and 
pistils,  110),  surrounded  by  two  sets  of  leaves 
or  envelopes  which  protect  them.  (Fig.  256.) 
The  latter  are  of  course  exterior  or  lower  than 
the  former,  which  in  the  bud  they  inclose. 

417.  The  Floral  Envelopes,  then,  are  of  two 
sorts,  and  occupy  two  circles,  one  above  or  ^ 
within  the  other.     Those  of  the  lower  circle, 

the  exterior  envelope  in  the  flower-bud,  form  the  Calyx  :  they  com- 


FIG.  256.  The  complete  flower  of  a  Crassula.  257,  Diagram  of  its  cross-section  in  the  bud, 
showing  the  relative  position  of  its  parts.  The  five  pieces  of  the  exterior  circle  are  sections  of 
the  sepals ;  the  next,  of  the  petals ;  the  third,  of  the  stamens  through  their  anthers ;  the  inner- 
most, of  the  five  pistils. 


228 


THE    FLOWER. 


monly  exhibit  the  green  color  and  have  much  the  appearance  of 
ordinary  leaves.  Those  of  the  inner  cir- 
cle, which  are  commonly  of  a  more  deli- 
cate texture  and  brighter  color,  and  form 
the  most  showy  part  of  the  blossom, 
compose  the  Corolla.  The  several 
parts  or  leaves  of  the  corolla  are  called 
Petals  :  and  the  leaves  of  the  calyx 
take  the  corresponding  name  of  Sepals. 
One  of  the  five  sepals  of  the  flower  rep- 
resented in  Fig.  256  is  separately  shown  in  Fig.  258 ;  and  one  of 
the  petals  in  Fig.  259.  The  calyx  and  corolla  taken  together,  or 
the  whole  floral  envelopes,  whatever  they  may  consist  of,  are 
sometimes  called  the  Perianth  {Perianthium  or  Perigonium). 

418.  The  Essential  Organs  of  the  flower  are  likewise  of  two  kinds, 
and  occupy  two  circles  or  rows,  one  within  the  other.  The  first  of 
these,  those  next  within  the  petals,  are  the  Stamens  (Fig.  260). 
A  stamen  consists  of  a  column  or  stalk,  called  the  Filament  (Fig. 
262,  a),  which  bears  on  its  summit  a  rounded 

body,  or  case,  termed  the  Anther  (h),  filled 
with  a  powdery  substance  called  Pollen,  which 
it  discharges  through  one  or  more  slits  or  open- 
ings. The  older  botanists  had  no  general  term 
for  the  stamens  taken  collectively,  analogous  to 
that  of  corolla  for  the  entire  whorl  of  petals, 
and  of  calyx  for  the  whorl  of  sepals.  A  name 
has,  however,  recently  been  proposed  for  the 
staminate  system  of  a  flower,  which  it  is  occasionally  convenient  to 
use  ;  that  of  Andr(ecium. 

419.  The  remaining,  or  seed-bearing  organs,  which  occupy  the 
centre  or  summit  of  the  flower,  to  whose  protection  and  perfec- 
tion all  the  other  parts  of  the  flower  are  in  some  way  subservient, 
are  termed  the  Pistils.  To  them  the  collective  name  of  GrNjs- 
ciUM  has  been  applied.  One  of  them  is  separately  shown  in  Fig. 
261.  This  is  seen  more  magnified  and  cut  across  in  Fig.  263 ; 
and  a  difierent  one,  longitudinally  divided,  so  as  to  exhibit  the 
whole  length  of  its  cavity,  or  cell,  is  represented  in  Fig.  264. 


FIG.  258.    A  separate  sepal:  259,  a  petal;  260,  a  stamen ;  and  261,  a  pistil  from  the  flower 
of  Fig.  256. 
FIG.  262,    A  stamen,  with  the  anther  (6)  discharging  its  pollen  :  a,  the  filament. 


FLORAL    ORGANS. 


229 


420.  A  pistil   is  distinguished  into  three  parts ;    namely,  the 

Ovary  (Fig.  264,  a),  the 
hollow  portion  at  the  base 
which  contains  the  Ovules, 
or  bodies  destined  to  be- 
come seeds ;  the  Style  (Z> ) , 
or  columnar  prolongation 
of  the  apex  of  the  ova- 
ry ;  and  the  Stigma  (c),  a 
2g^  portion  of  the   surface  of 

the  style  denuded  of  epi- 
dermis ;  sometimes  a  mere  point  or  a  small  knob 
at  the  apex  of  the  style,  but  often  forming  a  sin- 
gle or  double  line  running  down  a  part  of  its  in- 
ner face,  and  assuming  a  great  diversity  of  ap- 
pearance in  different  plants. 

421.  All  the  organs  of  the  flower  are  situated 
on,  or  grow  out  of,  the  apex  of  the  flower-stalk, 
into  which  they  are  said,  in  botanical  language, 

to  be  inserted,  and  which  is  called  the  Torus,  or  Receptacle. 
This  is  the  axis  of  the  flower,  to  which  the  floral  organs  are  at- 
tached (just  as  leaves  are  to  the  stem) ;  the  calyx  at  its  very  base  ; 
the  petals  just  within  or  above  the  calyx  ;  the  stamens  just  within 
the  petals ;  and  the  pistils  within  or  above  the  stamens. 

422.  Such  is  the  structure  of  a  complete  and  regular  flower  ; 
which  we  take  as  the  type,  or  standard  of  comparison.  The  calyx 
and  corolla  are  termed  protecting  organs.  In  the  bud,  they  en- 
velope the  other  parts :  the  calyx  sometimes  forms  a  covering 
even  for  the  fruit ;  and  when  it  retains  its  leaf-like  texture  and 
color,  it  assimilates  the  sap  of  the  plant  with  the  evolution  of 
oxygen  gas,  in  the  same  manner  as  do  true  leaves :  the  corolla 
elaborates  honey  or  other  secretions,  for  the  nourishment,  as  is 
supposed,  of  the  stamens  and  pistils.  But  neither  the  calyx  nor 
corolla  is  essential  to  a  flower,  one  or  both  being  not  unfrequently 
wanting.     The  stamens  and  pistils  are,  however,  essential  organs 


FIG.  263,  A  pistil  of  Crassula,  like  that  of  Fig.  261,  but  more  magnified,  and  cut  across 
through  the  ovary,  to  show  its  cell,  and  the  ovules  it  contains.  At  the  summit  of  the  style  is 
seen  a  somewhat  papillose  portion,  destitute  of  epidermis,  extending  a  little  way  down  the  in- 
ner face :  this  is  the  stigma. 

FIG.  264.  Vertical  section  of  a  pistil,  showing  the  interior  of  its  ovary,  a,  to  one  side  of 
which  are  attached  numerous  ovules,  d:  above  is  the  style,  b,  tipped  by  the  stigma,  c. 

20 


230  THE    FLOWER. 

of  the  flower,  since  both  are  necessary  to  the  production  of  seed. 
But  even  these  are  not  always  both  present  in  the  very  same  flow- 
er;  as  will  be  seen  when  we  come  to  notice  the  diverse  forms 
which  the  blossom  assumes,  and  to  compare  them  with  our  pattern 
flower. 

Sect.  II.     The   Theoretical   Structure    or   General   Mor- 
phology OF  the  Flower. 

423.  To  obtain  at  the  outset  a  correct  idea  of  the  flower,  it  is 
needful  here  to  consider  the  relation  which  its  organs  sustain  to  the 
organs  of  vegetation.  Taking  the  blossom  as  a  whole,  we  have 
recognized,  in  the  chapter  on  inflorescence  (377),  the  identity  of 
flower-buds  and  leaf-buds  as  to  situation,  &c.  Flowers,  conse- 
quently, are  at  least  analogous  to  branches,  and  the  leaves  of  the 
flower  to  ordinary  leaves. 

424.  But  the  question  which  now  arises  is,  whether  the  leaves 
of  the  stem  and  the  leaves  and  the  more  peculiar  organs  of  the 
flower  are  not  homologous  parts,  that  is  parts  of  the  same  funda- 
mental nature,  although  developed  in  different  shapes  that  they 
may  subserve  difl!erent  offices  in  the  vegetable  economy  ; — just  as 
the  arm  of  man,  the  fore-leg  of  quadrupeds,  the  wing-like  fore-leg 
of  the  bat,  the  true  wing  of  birds,  and  even  the  pectoral  fin  of 
fishes,  all  represent  one  and  the  same  organ,  although  developed 
under  widely  different  forms  and  subservient  to  more  or  less  dif- 
ferent ends.  The  plant  continues  for  a  considerable  time  to  pro- 
duce buds  which  develope  into  branches.  At  length  it  produces 
buds  which  expand  into  blossoms.  Is  there  an  entirely  new  sys- 
tem introduced  when  flowers  appear  ?  Are  the  blossoms  formed 
upon  such  a  different  plan,  that  the  general  laws  of  vegetation, 
which  have  sufficed  for  the  interpretation  of  all  the  phenomena  up 
to  the  inflorescence,  are  to  afford  no  further  clew  ?  Or,  on  the 
contrary,  now  that  peculiar  results  are  to  be  attained,  are  the  sim- 
ple and  plastic  organs  of  vegetation  —  the  stem  and  leaves  —  de- 
veloped in  new  and  peculiar  forms  for  the  accomplishment  of  these 
new  ends  ?  The  latter,  doubtless,  is  the  correct  view.  The  plant 
does  not  produce  essentially  new  kinds  of  organs  to  fulfil  the  new 
conditions,  but  adopts  and  adapts  the  old.  Notwithstanding  these 
new  conditions  and  the  successively  increasing  difference  in  ap- 
pearance, the  fundamental  laws  of  vegetation  may  be  traced  from 
the  leafy  branch  into  the  flower. 


ITS    GENERAL    MORPHOLOGY.  231 

425.  In  vegetation  no  new  organs  are  introduced  to  fulfil  any- 
particular  condition,  but  the  common  elements,  the  root,  stem,  and 
leaves,  are  developed  in  peculiar  and  fitting  forms  to  subserve 
each  special  purpose.  Thus,  the  same  organ  which  constitutes 
the  stem  of  an  herb,  or  the  trunk  of  a  tree,  we  recognize  in  the 
trailing  vine,  or  the  twiner,  spirally  climbing  other  stems,  in  the 
straw  of  Wheat  and  other  Grasses,  in  the  columnar  trunk  of  the 
Palm,  in  the  flattened  and  jointed  Opuntia,  or  Prickly  Pear,  and  in 
the  rounded,  lump-like  body  of  the  Melon-Cactus.  So,  also, 
branches  harden  into  spines  in  the  Thorn,  or,  by  an  opposite 
change,  become  flexible  and  attenuated  tendrils  in  the  Vine,  and 
runners  in  the  Strawberry;  or,  when  developed  under  ground, 
they  assume  the  aspect  of  creeping  roots,  and  sometimes  form 
thickened  rootstocks,  as  in  the  Calamus,  or  tubers,  as  in  the  Po- 
tato. But  the  type  is  readily  seen  through  these  disguises.  They 
are  all  mere  modifications  of  the  stem.  The  leaves,  as  we  have 
already  seen,  appear  under  a  still  greater  variety  of  forms,  some 
of  them  as  widely  different  from  the  common  type  of  foliage  as 
can  be  imagined ;  such,  for  example,  as  the  thickened  and  obese 
leaves  of  the  Mesembryanthemums  ;  the  intense  scarlet  or  crimson 
floral  leaves  of  the  Euchroma,  or  Painted  Cup,  of  the  Poinsettia 
of  our  conservatories,  and  of  several  Mexican  Sages  ;  the  tendrils 
of  the  Pea  tribe  ;  the  pitchers  of  Sarracenia  (Fig.  223),  and 
also  those  of  Nepenthes  (Fig.  225),  which  are  leaf,  tendril,  and 
pitcher  combined.  The  leaves  also  appear  under  very  different 
aspects  in  the  same  individual  plant,  according  to  the  purposes 
they  are  intended  to  subserve.  The  first  pair  of  leaves,  or  cotyle- 
dons, when  gorged  with  nutritive  matter  for  the  supply  of  the  ear- 
liest wants  of  the  embryo  plant,  as  in  the  Bean  and  Almond  (Fig. 
97),  would  seem  to  be  peculiar  organs.  But  when  they  have  dis- 
charged this  special  office  in  germination,  by  yielding  to  the  young, 
plant  the  store  of  nourishment  with  which  they  are  laden,  they 
throw  off  their  disguise,  and  assume,  with  more  or  less  distinct- 
ness, the  color  and  appearance  of  ordinary  foliage ;  while  in  other 
cases,  as  in  the  Convolvulus,  &c.,  they  are  green  and  foliaceous 
from  the  first.  As  the  stem  elongates,  the  successive  leaves  vary 
in  form  or  size,  according  to  the  varying  vigor  of  vegetation.  In 
our  trees,  we  trace  the  last  leaves  of  the  season  into  bud-scales ; 
and  in  the  returning  spring  we  may  often  observe  the  innermost 
scales  of  the  expanding  leaf-buds  to  resume,  the  first  perhaps  im- 


232 


THE    FLOWER. 


perfectly,  but  the  ensuing  ones  successfully,  the  appearance  and 
the  ordinary  office  of  leaves  (146). 

426.  The  analogies  of  vegetation  w^ould  therefore  suggest,  that, 
in  flowering,  the  leaves,  no  longer  developing  as  mere  foliage,  are 
now  wrought  into  new  forms,  to  subserve  peculiar  purposes.  In 
the  chapter  on  Inflorescence,  we  have  already  shown  that  the  ar- 
rangement and  situation  of  flowers  upon  the  stem  conform  to  this 
idea.  In  this  respect,  flowers  are  absolutely  like  branches.  The 
aspect  of  the  floral  envelopes  favors  the  same  view.  We  discern 
the  typical  element,  the  leaf,  in  the  calyx;  and  again,  more  deli- 
cate and  refined,  in  the  petals.  In  numberless  instances,  we  ob- 
serve a  regular  transition  from  ordinary  leaves  into  sepals,  and 
from  sepals  into  petals.     And,  while  the  petals  are  occasionally 


green  and  herbaceous,  the  undoubted  foliage  sometimes  assumes  a 

FIG.  265.  Open  flower,  with  a  flower-bud  ancj  leaf  of  the  White  Wat«r-Lily  (Nymphsea 
odorata) ;  the  inner  petals  passing  into  stamens.  266.  A  flower  with  all  the  parts  around  the 
pistil  cut  away  except  one  of  the  petaloid  stamens,  one  intermediate,  and  one  proper  stamen, 
267.  An  inner  petal,  with  the  imperfect  rudiments  of  an  anther  at  the  tip.  268.  Transverse 
section  of  an  ovary. 


ITS    GENERAL    MORPHOLOGY.  233 

delicate  texture  and  the  brightest  hues  (425).  The  perfect  grada- 
tion of  leaves  or  bracts  into  sepals  is  extremely  common.  The 
transition  of  sepals  into  petals  is  exemplified  in  almost  every  case 
where  there  are  more  than  two  rows  of  floral  envelopes ;  as  in  the 
Magnolia,  and  especially  in  the  White  Water-Lily,  the  lllicium,  or 
Star  Anise  of  the  Southern  States,  and  the  Calycanthus,  or  Caro- 
lina Allspice,  which  present  several  series  of  floral  envelopes,  all 
nearly  alike  in  color,  texture,  and  shape  ;  but  how  many  of  the 
innermost  are  to  be  called  petals,  and  how  the  remainder  are  to  be 
divided  between  sepals  and  bracts,  is  entirely  a  matter  of  arbitrary 
opinion.  In  fact,  the  only  real  difl?erence  between  the  calyx  and 
corolla  is,  that  the  former  is  the  outer,  and  the  latter  an  inner  se- 
ries of  floral  envelopes.  Sometimes  the  gradation  extends  one 
step  farther,  and  exhibits  an  evident  transition  of  petals  into  sta- 
mens ;  showing  that  these  are  of  the  same  fundamental  nature  as 
the  floral  envelopes,  which  are  manifestly  traceable  back  to  leaves. 
The  White  Water-Lily  (Fig.  265)  exhibits  this  latter  transition,  as 
evidently  as  that  of  sepals  into  petals.  Here  the  petals  occupy 
several  whorls,  and,  while  the  exterior  are  nearly  undistinguishable 
from  the  calyx,  the  inner  are  reduced  into  organs  which  are  neither 
well-formed  petals  nor  stamens,  but  intermediate  between  the  two. 
They  are  merely  petals  of  a  smaller  size,  with  their  summits  con- 
tracted and  transformed  into  imperfect  anthers,  containing  a  iew 
grains  of  pollen  :  those  of  the  series  next  within  are  more  reduced 
in  size,  and  bear  perfect  anthers  at  the  apex ;  and  a  still  further 
reduction  of  the  lower  part  of  the  petal  completes  the  transition 
into,  stamens  of  ordinary  appearance. 

427.  Transitions,  or  intermediate  states,  between  petals  and  sta- 
mens occur  in  numerous  cases.  These  two  are  not  only  adjacent 
organs,  but  they  appear  to  have  very  intimate  relations,  to  which 
we  may  allude  in  another  place.  But  similar  transitions  between 
such  specialized,  and,  as  it  were,  antagonistic  organs,  as  the  stamens 
and  the  pistils  would  not  be  expected  normally  to  occur ;  nor  is 
there  any  such  regular  instance  known.  Yet  they  are  not  unfre- 
quently  met  with  in  monstrous  blossoms,  as  occasionally  in  the 
Oriental  Poppy  in  gardens,  in  the  Houseleek,  and  in  certain  Wil- 
lows. These  are  monsters  it  is  true  ;  but  the  study  of  monstrosi- 
ties often  throws  much  light  upon  the  regular  structure. 

428.  The  regular  transformation,  or  metamorphosis  (if  we  may 
use  that  somewhat  ambiguous  term),  takes  an  upward  course,  from 

20* 


231 


THE    FLOWER. 


leaves  into  sepals,  from  sepals  into  petals,  and  from  the  latter  into 
stamens,  or  even  into  pistils.  We  trace  the  typical  leaf  forward 
into  the  floral  envelopes,  and  thence  into  the  essential  organs  of  the 
blossom.  Now  if  these  organs  be,  as  it  were,  leaves  developed  in 
peculiar  states  under  the  controlling  agency  of  a  power  which  has 
overborne  the  ordinary  forces  of  vegetation,  they  must  always  have 
a  tendency  to  develope  In  their  primitive  form,  when  the  causes 
that  govern  the  production  of  blossoms  are  interfered  with.  They 
may  then  reverse  the  spell,  and  revert  into  some  organ  below  them 
in  the  series,  as  from  stamens  into  petals,  or  pass  at  once  into  the 
state  of  ordinary  leaves.  That  is,  organs  which  from  their  position 
should  be  stamens  or  pistils  may  develope  as  petals  or  floral  leaves, 
or  in  the  form  of  ordinary  leaves.  Such  cases  o^  retrograde  meta- 
morphosis  frequently  occur  in  cultivated  flowers,  and  occasionally 
in  some  spontaneous  plants. 

429.  Thus  we  meet  with  the  actual  reconversion  of  what  should 
he  a  pistil  into  a  leaf  very  frequently  in  the 
double  garden  Cherry,  either  completely 
(Fig.  269),  or  else  incompletely,  so  that  the 
resulting  organ  (as  in  Fig.  270)  is  something 
intermediate  between  the  two.  The  change 
of  what  should  he  stamens  into  petals  is  of 
common  occurrence  in  what  are  called  double 
and  semi-double  flowers  of  the  gardens ;  as 
in  Roses,  Camellias,  Carnations,  &c.  When 
such  flowers  have  many  stamens,  these  disap- 
pear as  the  supernumerary  petals  increase  in 
number ;  and  the  various  bodies  that  may  be 
often  observed,  intermediate  between  perfect 
stamens  (if  any  remain)  and  the  outer  row  of  petals,  —  from  im- 
perfect petals  with  a  small  lamina  tapering  into  a  slender  stalk,  to 
those  which  bear  a  small  distorted  lamina  on  one  side  and  a  half- 
formed  anther  on  the  other,  —  plainly  reveal  the  nature  of  the 
transformation  that  has  taken  place.  The  garden  Columbine  often 
affords  beautiful  illustrations  of  this  kind.  Carried  a  step  farther, 
the  pistils  likewise  disappear,  to  be  replaced  by  a  rosette  of  petals, 
as  in  double  Buttercups.     It  is  wrong  to  suppose,  however,  that  the 


FIG.  269.    A  small  leaf  ia  place  of  a  pistil  from  the  centre  of  a  flower  of  the  double  Cherry. 
270.  An  organ  intermediate  between  a  leaf  and  a  pistil,  from  a  similar  flower. 
FIG.  271.    Leaflet  of  a  Bryophyllum,  developing  buds  along  its  margins. 


ITS    GENERAL    MORPHOLOGY. 


235 


increase  in  the  number  of  the  petals  of  double  flowers  is  altogether 
at  the  expense  of  the  sta- 
mens and  pistils.  In  such 
cases  the  petals  themselves 
are  prone  to  double^  or  to 
multiply  in  number. 

430.  In  full  double  But- 
tercups we  may  often  no- 
tice a  tendency  of  the  ro- 
sette of  petals  to  turn  green, 
or  to  retrograde  still  far- 
ther into  foliaceous  organs. 
And  there  is  a  monstrous 
state  of  the  Strawberry- 
blossom,  well  known  in 
Europe,  in  which  all  the 
floral  organs  revert  into 
green  sepals,  or  imperfect 
leaves.  The  annexed  il- 
lustration (Fig.  272)  exhibits  a  similar  retrograde  metamorphosis 
in  a  flower  of  the  White  Clover,  where  the  calyx,  pistil,  &;c.,  are 
still  recognizable,  although  partially  transformed  into  leaves.     We 

may  observe  that  the  ovary,  which  has 
opened  down  one  side,  bears  on  each 
edge  a  number  of  small  and  imperfect 
leaves ;  much  as  the  ordinary  leaves, 
or  rather  leaflets,  of  Bryophyllum  are 
apt  to  develope  rudimentary  tufts  of 
leaves,  or  buds,  on  their  margins  (Fig. 
271),  which  soon  grow  into  little  plant- 
lets.  This  reversion  of  a  whole  blos- 
som into  foliaceous  parts  has  been 
termed  chlorosis,  from  the  green  color 
thus  assumed. 

431.  Somewhat  different  is  the  ret- 
rograde metamorphosis  which  is  occa- 
sionally seen  in  the  production  of  a  leafy  branch  from  the  centre  of 

FIG.  272.    A  flower  of  the  common  White  Clover  reverting  to  a  leafy  branch,  after  Turpin. 

FIG.  273.  Retrograde  metamorphosis  of  a  flower  of  the  Fraxinella  of  the  gardens,  from 
Lindley's  Theory  of  Horticulture;  an  internode  elongated  just  above  the  stamens,  and  bearing 
a  whorl  of  green  leaves. 


236 


THE    FLOWER. 


a  flower^  or  of  one  flower  out  of  the  centre  of  another  (as  rose-buds 
out  of  roses).  Here  the  receptacle,  or  axis  of 
the  flower,  resumes  the  ordinary  growth,  or  vege- 
tation, of  the  branch.  This  more  commonly 
takes  place  after  the  formation  of  the  floral  en- 
velopes and  stamens,  but  before  the  pistils  ap- 
pear ;  as  in  Fig.  273.  The  appearance  of  a  leafy 
branch  from  the  summit  of  a  Pear  (as  in  Fig. 
274)  is  similarly  explained.  So,  likewise,  in 
very  wet  and  warm  springs,  some  of  the  flower- 
buds  of  the  Pear  and  Apple  are  occasionally 
forced  into  active  vegetative  growth,  so  as  com- 
pletely to  break  up  the  flower,  and  change  it  into 
an  ordinary  leafy  branch. 

432.  In  such  cases  the  terminal  bud  goes  on 
to  grow,  —  contrary  to  the  normal  condition,  in 
which  the  flower  arrests  all  further  development 
of  the  axis  that  bears  it.  An  analogous  monstros- 
ity sometimes  occurs,  in  which  axillary  buds 
(148)  are  developed  in  the  flower.  Its  organs 
thus  exhibit  a  distinguishing  characteristic  of  leaves,  viz.  the  pro- 
duction of  buds  in  their  axils ;  which  develope  either  as  branches 
or  as  new  axes  at  once  terminated  by 
blossoms.  Flowers  have  thus  been  met 
with  in  the  axils  of  the  petals,  as  in  Fig. 
275,  and  sometimes  even  in  those  of  the 
stamens  or  pistils.  Monstrosities  of  this 
sort  are  common  in  the  Rose.  Of  the 
same  kind  are  most  of  those  cases  in 
which  one  or  more  fruits,  such  a^  ap- 
pies  or  pears,  grow  out  of  another  fruit. 

We  have  met  with  flowers  of  Clarkia  elegans  which  bore  an  im- 
perfect blossom  in  the  axil  of  each  petal. 

433.  The  irresistible  conclusion  from  all  such  evidence  is,  that 
the  flower  is  one  of  the  forms  —  the  ultimate  form  —  under  which 
branches  appear ;  that  the  leaves  of  the  stem,  the  leaves  or  petals 
of  the  flower,  and  even  the  stamens  and  pistils,  are  all  forms  of  a 


FIG.  274.    A  monstroua  pear,  prolonged  into  a  leafy  branch,  from  Bonnet. 
FIG.  275,    A  flower  of  the  False  Bittersweet  (Celastrus  scandens),  producing  other  flowers 
in  the  axjls  of  the  petals,  from  Turpi  n. 


ITS  GENERAL  MORPHOLOGY.  237 

common  type,  only  differing  in  their  special  development.  And  it 
may  be  added,  that  in  an  early  stage  of  development  they  all  ap- 
pear alike.  That  which,  under  the  ordinary  laws  of  vegetation, 
would  have  developed  as  a  leafy  branch,  does,  in  a  special  case 
and  according  to  some  regular  law,  finally  develope  as  a  flower ; 
its  several  organs  appearing  under  forms,  some  of  them  slightly 
and  others  extremely  different  in  aspect  and  in  office  from  the  fo- 
liage. But  they  all  have  a  common  nature  and  a  common  origin, 
or,  in  other  words,  are  homologous  parts  (424).  They  all  answer 
respectively  to  the  leaf  part  of  successive  phytons. 

434.  Now,  as  we  have  no  general  name  to  comprehend  all 
those  organs  which,  as  leaves,  bud-scales,  bracts,  sepals,  petals, 
stamens,  &c.,  successively  spring  from  the  ascending  axis  or  stem, 
having  ascertained  their  essential  identity,  we  naturally,  and  in- 
deed necessarily,  take  some  one  of  them  as  the  type^  and  view  the 
others  as  modifications  or  metamorphoses  of  it.  The  leaf  is  the 
form  which  earliest  appears,  and  is  the  most  general  of  all  the  or- 
gans of  the  vegetable ;  it  is  the  form  which  is  indispensable  to 
vegetation  in  its  perfected  development,  in  which  it  plays,  as  we 
have  seen,  the  most  important  part ;  it  is  the  form  into  which  all 
the  floral  organs  may  sometimes  be  traced  back  by  numerous 
gradations,  and  to  which  they  are  liable  to  revert  when  flowering 
is  disturbed  and  the  proper  vegetative  forces  again  prevail.  Hence 
the  leaf  may  be  properly  assumed  as  the  type  or  pattern,  to  which 
all  the  others  are  to  be  referred.  When,  therefore,  the  floral  or- 
gans are  called  modijied  or  metamorphosed  leaves  (terms  which  we 
have  avoided  almost  entirely,  as  liable  to  convey  an  erroneous  im- 
pression), it  is  not  to  be  supposed  that  a  petal  has  ever  actually 
been  a  green  leaf,  and  has  subsequently  assumed  a  more  delicate 
texture  and  hue,  or  that  stamens  and  pistils  have  previously  existed 
in  the  state  of  foliage ;  but  only  that  what  is  fundamentally  one 
and  the  same  organ  developes,  in  the  progressive  evolution  of  the 
plant,  under  each  or  any  of  these  various  forms.  When  the  indi- 
vidual organ  has  once  fairly  begun  to  develope,  its  destiny  is  fixed. 

435.  The  theory  of  vegetable  morphology  may  be  expressed  in 
other,  and  more  hypothetical  or  transcendental  forms.  We  have 
preferred  to  enunciate  it  in  the  simplest  and  most  general  terms. 
But,  under  whatever  particular  formula  expressed,  its  adoption  has 
not  only  greatly  simplified,  but  has  thrown  a  fllood  of  light  over  the 
whole   of  Structural  Botany,  and   has   consequently  placed    the 


238  THE    FLOWER. 

whole  logic  of  Systematic  Botany  upon  a  new  and  philosophical 
basis..  Our  restricted  limits  will  not  allow  us  to  trace  its  histor- 
ical development.  Suffice  it  to  say,  that  the  idea  of  the  essen- 
tial identity  of  the  floral  organs  and  the  leaves  was  distinctly  pro- 
pounded by  Linneeus,*  about  the  middle  of  the  last  century.  It 
was  newly  taught  by  Caspar  Frederic  Wolff,  about  twenty  years 
later,  and  again,  after  the  lapse  of  nearly  twenty  years  more,  by 
the  celebrated  Goethe,  who  was  entirely  ignorant,  as  apparently 
were  his  scientific  contemporaries,  of  what  Linnaeus  and  Wolff  had 
written  on  the  subject.  His  curious  and  really  scientific  treatise 
was  as  completely  forgotten  or  overlooked  as  the  significant  hints 
of  Linnaeus  had  been.  In  advance  of  the  science  of  the  day,  and 
more  or  less  encumbered  with  hypothetical  speculations,  none  of 
these  writings  appear  to  have  exerted  any  influence  over  the 
progress  of  the  science,  until  it  had  reached  a  point,  early  in  the 
present  century,  when  the  nearly  simultaneous  generalizations  of 
several  botanists,  following  different  clews,  were  leading  inevitably 
to  the  same  conclusions.  Ignorant  of  the  writings  of  Goethe  and 
Wolff,  De  Candolle  was  the  first  to  devfelope,  from  an  independent 
and  original  point  of  view,  the  idea  of  symmetry  in  the  flower ; 
that  the  plan,  or  type,  of  the  blossom  is  regular  and  symmetrical, 
but  that  this  symmetry  is  more  or  less  modified  or  disguised  by 
secondary  influences,  giving  rise  to  various  deviations,  such  as 
those  which  we  are  soon  to  consider.  The  reason  of  the  prevail- 
ing symmetrical  arrangement  of  parts  in  the  blossom  has  only 
recently  been  made  apparent,  in  the  investigation  of  the  laws 
of  phyllotaxis  (234)  ;  from  which  it  appears  that  the  general  ar- 
rangement of  the  leaves  upon  the  leafy  stem  is  carried  out  into 
the  flower. 


Sect.  III.  The  Symmetry  of  the  Flower. 

436.  A  Symmetrical  Flower  is  one  which  has  an  equal  number  of 
parts  in  each  circle  or  whorl  of  organs ;  as,  for  example,  in  Fig. 
256,  where  there  are  five  sepals,  five  petals,  five  stamens,  and  five 
pistils.    It  is  not  less  symmetrical,  although  less  simple,  when  there 


*  "  Principium  florum  et  foliorum  idem  est.  Principium  gemmarum  et 
foliorum  idem  est.  Gemma  constat  foliorum  rudimentis.  Perianthium  sit 
ex  connatis  foliorum  rudimentis,"  etc.    Philosophia  Botanica^  p.  301. 


ITS    SYMMETRY. 


239 


are  two  or  more  circles  of  the  same  kind  of  organ ;  as  in  Sedum, 
where  there  are  two  sets  of  stamens,  five  in  each ;  in  the  Barberry, 
where  there  are  two  or  more  sets  of  sepals,  two 
of  petals,  and  two  of  stamens,  three  in  each 
set,  &c.  A  complete  jlower  (as  already  de- 
fined, 416)  is  one  that  possesses  both  sorts  of 
floral  envelopes,  calyx  and  corolla,  and  both 
essential  organs,  viz.  stamens  and  pistils. 

437.  The  simplest  possible  complete  and 
symmetrical  flower  would  be  one  with  the  ca- 
lyx of  a  single  sepal,  a  corolla  of  a  single  pet- 
al, a  single  stamen,  and  a  single  pistil ;  such 
as  is  represented  in  the  annexed  diagram,  in 
connection  with  the  two-ranked  arrangement 
of  the  leaves  (Fig.  276).  Each  constituent 
of  the  blossom  represents  a  phyton,  with  its 
stem  part  reduced  to  a  minimum,  and  its  leaf 
part  developed  in  a  peculiar  way,  according 
to  the  rank  it  sustains  and  the  oflice  it  is  to 
fulfil.  That  there  are  short  internodes  be- 
tween consecutive  organs  in  the  flower  is 
usually  apparent  on  minute  inspection  of  its 
axis,  or  receptacle ;  and  some  of  them  are 
conspicuously  prolonged  in  certain  cases. 
But  they  are  commonly  undeveloped,  like  the 
axis  of  a  leaf-bud,  so  that  the  organs  are 
brought  into  juxtaposition  on  a  short,  mostly 
conical  receptacle,  and  the  higher  or  later- 
formed  parts  are  interior  or  inclosed  by  the 
lower. 

438.  Perhaps  the  exact  case  of  a  flower  at 
once  so  complete  and  so  simple  is  not  to  be 
met  with.     For,  when  the  stamens  and  pis- 
tils are  thus  reduced  to  the  minimum  number,  the  floral  envelop 
one  or  both,  commonly  disappear,  a     n  the  Mare's-tail  (see  Ord. 
Onagracese).     Nor  is  the  production    f  seed  often  left  to  depend 
upon  a  single  organ  ;  but  the  essential,  and  with  them  the  protect- 


FIG.  276.  Diagram  of  a  plant,  with  a  distichous  arrangement  of  the  phytons,  carried 
through  the  complete  flower,  of  the  simplest  kind,  consisting  of,  a,  a  sepal;  b,  a  petal;  c,  a 
stamen  ;  and  d,  a  pistil :  br  is  the  bract  or  uppermost  proper  leaf. 


240 


THE    FLOWER. 


ing  organs,  are  generally  multiplied  in  each  flower,  so  as  greatly  to 
diminish  the  chances  of  failure.  Thus  we  find  a  circle  or  whorl 
of  each  kind  of  organ,  and  often  two  or  three  circles,  or  a  still  lar- 
ger and  apparently  indefinite  number  of  parts.  In  fact,  the  floral 
organs  usually  occur  in  twos,  threes,  fours,  or  fives,  and  the  same 
number  commonly  prevails  through  the  several  parts  of  the  flower 
(except  when  interfered  with  by  some  of  the  disturbing  causes 

hereafter  mentioned), 
which  therefore  dis- 
plays a  symmetrical 
arrangement,  or  a  man- 
ifest tendency  towards 
it.* 

439.  Having  already 
noticed  the  symmetri- 
cal arrangement  of  the  foliage 
(234-252),  and  remarked  the  transition  of  ordi- 
nary leaves  into  those  of  the  blossom  (426),  we 
naturally  ssek  to  bring  the  two  under  the  same 
general  laws,  and  look  upon  each  floral  whorl  as 
answering  either  to  a  cycle  of  alternate  leaves 
with  their  respective  internodes  undeveloped 
(237-239),  or  to  a  pair  or  verticil  of  opposite  or 
verticillate  leaves  (250,  251).  Thus,  the  simplest 
combination,  where  the  organs  are  dimerous,  or 
in  twos,  may  be  compared  with  the  alternate  two- 
ranked  arrangement  (237),  the  calyx,  the  corolla, 
stamens,  &c.,  each  consisting  of  one  cycle  of  two 
elements ;    or  else  with  the  case  of  opposite  leaves  (250),  when 


*  Terms  expressive  of  the  number  of  parts  which  compose  each  whorl  or 
kind  of  organ  are  formed  of  the  Greek  numerals  combined  with  jiepos,  a  part. 
Thus  a  flower  with  only  one  organ  of  each  kind,  as  in  the  diagram,  Fig.  276, 
is  monomerous ;  a  flower  or  a  whorl  of  two  organs  is  dimerous  (Fig.  298)  ;  of 
three  (as  in  Fig.  277),  trimerous;  of  four,  tetramerous  (Fig.  280)  ;  of  five  (as  in 
Fig.  284),  pentamerous;  of  six,  hexamerous;  often,  decamerous,  &c. 


FIG.  277.    Parts  of  a  symmetrical  trimerous  flower  (Tillaea  muscosa) :  a,  calyx;  b,  corolla; 

c,  stamens  ;  d,  pistils. 

FIG.  278.  Ideal  plan  of  a  plant,  with  the  simple  stem  terminated  by  a  symmetrical  penta- 
merous flower ;  the  different  sets  of  organs  separated  to  some  distance  from  each  other,  to  show 
the  relative  situation  of  the  parts;  one  of  each,  namely,  a,  a  sepal,  b,  a  petal,  c,  a  stamen,  and 

d,  a  pistil,  also  shown,  enlarged. 


ALTERNATION  OF  THE  FLORAL  ORGANS.  241 

each  set  would  answer  to  a  pair  of  leaves.  So,  likewise,  the  or- 
gans of  a  trimerous  flower  (viz.  one  with  its  parts  in  threes,  as  in 
Fig.  277)  may  be  taken,  each  set  as  a  cycle  of  alternate  leaves  of 
the  tristichous  mode  (171),  with  the  axis  depressed,  which  would 
throw  the  parts  into  successive  whorls  of  threes,  or  as  a  proper  ver- 
ticil of  three  leaves  ;  while  those  of  a  pentamerous  or  quinary  flower 
(with  the  parts  in  fives,  as  in  Fig.  278)  would  answer  to  the  cycles 
of  the  f  arrangement  (239)  of  alternate  leaves,  or  to  proper  five- 
leaved  verticils.  So  the  whorls  of  a  tetramerous  flower  are  to  be 
compared  with  the  case  of  decussating  opposite  leaves  (250)  com- 
bined two  by  two,  or  directly  with  quaternary  verticillate  leaves ; 
either  of  which  would  give  sets  of  parts  in  fours. 

440.  The  Alternation  of  the  Floral  Organs.  We  learn  from  obser- 
vation that  the  parts  of  the  successive  circles  of  the  flower  almost 
universally  alternate  with  each  other.  The  five  petals  of  the  flower 
represented  in  Fig.  256,  for  example,  are  not  opposed  to  the  five 
sepals,  that  is  situated  directly  above  or  before  them,  but  alternate 
with,  or  stand  over  the  intervals  between  them  ;  the  five  stamens 
in  like  manner  alternate  with  the  petals,  and  the  five  pistils  with 
the  stamens,  as  is  shown  in  the  diagram.  Fig.  257.  The  same  is 
the  case  in  the  trimerous  flower.  Fig.  277 ;  and  in  fact  this  is  the 
regular  rule,  the  few  exceptions  to  which  have  to  be  separately 
accounted  for. 

441.  This  alternation  comports  with  the  more  usual  phyllotaxis 
in  opposite  and  verticillate  leaves,  where  the  successive  pairs  de- 
cussate, or  cross  each  other  at  right  angles  (250),  or  the  leaves  of 
one  verticil  severally  correspond  to  the  intervals  of  that  underneath, 
making  twice  as  many  vertical  ranks  as  there  are  parts  in  the 
whorl  (251).  The  alternation  of  the  floral  organs  is  therefore 
most  readily  explained  on  the  assumption  that  the  several  circles 
are  true  decussating  verticils ;  when  it  only  remains  to  discover 
the  real  connection  between  the  opposite-leaved  or  verticillate  and 
the  spiral  phyllotaxis,  and  to  obtain  some  expression  which  will 
harmonize  the  two  modes ;  both  of  which  are  often  met  with  on 
the  same  axis.  But  the  inspection  of  a  flower-bud  with  the 
parts  imbricated  in  aestivation  (492)  shows  that  the  several  mem- 
bers of  the  same  set  do  not  originate  exactly  in  the  same  plane. 
The  five  petals,  for  example,  in  the  cross-section  of  the  pentame- 
rous  blossom  shown  in  Fig.  257  (and  the  same  arrangement  is  still 
more  frequently  seen  in  the  calyx),  are  so  situated,  that  two  are 

21 


242 


THE    FLOWER. 


exterior  in  the  bud,  and  therefore  inserted  lower  on  the  axis  than 
the  rest,  the  third  is  intermediate,  and  two  others  are  entirely 
interior,  or  inserted  higher  than  the  rest.  In  fact,  they  exactly 
correspond  with  a  cycle  of  the  quincuncial,  or  five-ranked,  spiral 
arrangement,  projected  on  an  extremely  abbreviated  axis,  or  on  a 
horizontal  plane,  as  is  at  once  seen  by  comparison  with  Fig.  172, 
173.  Also  when  the  parts  are  in  fours,  two  are  almost  always  ex- 
terior in  the  bud,  and  two  interior.  Moreover,  whenever  the  floral 
envelopes,  or  the  stamens  or  pistils,  are  more  numerous,  so  as  to 
occupy  several  rows,  the  spiral  disposition  is  the  more  manifest. 
It  is  most  natural,  accordingly,  to  assume  that  the  calyx,  corolla, 
stamens,  &c.,  of  a  pentamerous  flower  are  each  a 
depressed  spiral  or  cycle  of  the  f  mode  of  phyllo- 
taxis  (239),  and  those  of  the  trimerous  flower  are 
similar  spirals  of  the  -J  mode  (238).  But  then  the 
parts  of  the  successive  cycles  should  be  superposed, 
or  placed  directly  before  each  other  on  the  de- 
pressed axis  (Fig.  171) ;  whereas,  on  the  contrary, 
they  almost  always  alternate  with  each  other  in  the  flower,  as 
in  the  annexed  diagram  (Fig.  279). 

442.  To  reconcile  this  alternation  with  the  laws  of  phyllotaxis 
in  alternate  leaves,  Prof.  Adrien  de  Jussieu  has  advanced  an  in- 
genious hypothesis.  He  assumes  the  ■f'-^  spiral  arrangement  (241) 
as  the  basis  of  the  floral  structure  both  of  the  trimerous  and  penta- 
merous flower,  (at  least  when  the  envelopes  are  imbricated  in  the 
bud,)  this  being  the  one  that  brings  the  successive  parts  most 
nearly  into  alternation,  either  in  threes  or  in  fives ;  as  will  readily 
be  observed  on  inspection  of  the  tabular  projection  of  that  mode, 
given  on  page  147.  The  difference  between  the  position  of  parts 
in  regular  alternation,  whether  in  threes  or  fives,  and  that  assigned 
by  an  accurate  spiral  projection  of  the  f^  mode,  is  very  slight  as 
respects  most  of  the  organs,  and  in  none  does  the  deviation  exceed 
one  thirteenth  of  the  circumference ;  —  a  quantity  which  becomes 
nearly  insignificant  on  an  axis  so  small  as  that  of  most  flowers,  es- 
pecially towards  its  narrowed  apex.  Moreover,  if  the  interior  or- 
gans of  a  regular  and  symmetrical  flower  were  thus  to  originate  in 
the  bud  nearly  in  alternation  with  those  that  precede  them,  they 
would  almost  necessarily  be  pushed  a  little,  as  they  develope,  into 

FIG.  279.  Cross-section  of  the  flower-bud  of  the  trimerous  Tillaea,  Fig.  277,  to  show  tlie  al- 
ternation of  parts. 


ITS    POSITION    IN    RESPECT    TO    THE    BRACT   AND    AXIS.  243 

the  position  of  least  pressure,  and  thus  fall  into  these  intervals  with 
all  the  exactness  that  is  actually  found  in  nature.  For  in  these  liv- 
ing bodies,  endowed  as  they  are  with  plasticity  and  a  certain  pow- 
er of  adaptation  to  circumstances,  the  positions  assumed  are  not 
mathematically  accurate  ;  and  the  effect  of  unequal  pressure  in  the 
bud  in  throwing  the  smaller  parts  more  or  less  out  of  their  normal 
position  may  be  observed  in  almost  any  irregular  flower.  More- 
over, in  all  the  forms  of  phyllotaxis  from  ■f'-^  onwards,  it  is  doubtful 
whether  what  we  term  vertical  ranks  are  exactly  superposed.  In 
tracing  them  onward  to  some  extent,  we  perceive  indications  of 
a  curviserial  arrangement,  where  the  superposition  is  continually 
approximated,  but  is  never  exactly  attained. 

443.  When,  therefore,  the  floral  circles  consist  of  parts  which 
are  evidently  developed  in  the  same  horizontal  plane  (494),  they 
are  most  simply  viewed  as  decussating  verticils,  —  as  formed  after 
the  manner  of  opposite  leaves.  When  they  are  imbricated  in  the 
bud  (492),  or  show  in  other  ways  a  spiral  disposition  of  parts,  we 
may  conceive  that  the  law  of  alternation  is  conformed  to  in  the 
manner  which  Jussieu  has  suggested,  or  in  some  such  way.  How- 
ever explained,  we  cannot  fail  to  discern  an  end  attained  by  such 
arrangement,  namely,  a  disposition  of  parts  which  secures  the 
greatest  economy  of  space  on  an  abbreviated  axis,  and  the  greatest 
freedom  from  mutual  pressure. 

444.  Position  of  the  Flower  as  respects  the  Axis  and  subtending  Bract. 

All  axillary  flowers  are  situated  between  a  leaf  and  the  stem,  or, 
which  is  the  same  thing,  between  a  bract  and  the  axis  of  inflores- 
cence. These  two  fixed  points  enable  us  to  indicate  the  relative 
position  of  the  parts  of  the  floral  circles  with  precision.  That  part 
of  the  flower  which  lies  next  the  leaf  or  bract  from  whose  axil  it 
arises  is  said  to  be  anterior,  or  inferior  (lower) :  that  which  is 
diametrically  opposite  or  next  the  axis  is  posterior,  or  superior 
(upper).*  It  is  important  to  notice  the  relative  poshion  of  parts  in 
this  respect.  This  is  shown  in  a  proper  diagram  by  drawing  a 
section  of  the  bract  in  its  true  position  under  the  section  of  the 
flower-bud,  as  in  Fig.  282 :  that  of  the  axis  is  necessarily  diamet- 


*  As  if  these  were  not  terms  enough,  sometimes  the  organ  or  side  of  the 
flower  which  looks  towards  the  bract  is  likewise  called  exterior,  and  the  organ 
or  side  next  the  axis,  interior;  but  these  terms  should  be  kept  to  designate  the 
relative  position  of  the  members  of  the  floral  circles  in  eestivation  (490). 


244 


THE    FLOWER. 


rically  opposite,  and  its  section  is  sometimes  indicated  by  a  dot  or 
small  circle.  In  an  axillary  tetramerous  flower  one  of  the  sepals 
will  be  anterior,  one  posterior,  and  two  lateral,  or  right  and  left; 
as  in  the  annexed  diagram  of  a  Cruciferous  blossom  (Fig.  280) ; 


while  the  petals,  alternating  with  the  sepals,  occupy  intermediate 
positions,  or  consist  of  an  anterior  and  a  posterior  pair ;  while  the 
stamens,  again,  correspond  to  the  sepals  in  position.  A  pentame- 
rous  axillary  flower,  having  an  odd  number  of  parts,  will  have 
either  one  sepal  superior  or  posterior  and  two  inferior  or  anterior 
(as  in  Rhus,  Fig.  281),  or  else,  vice  versa^  with  one  inferior  and 
two  superior,  as  in  papilionaceous  flowers  (Fig.  282) :  in  both  cases 
the  two  remaining  sepals  are  lateral.  The  petals  will  consequently 
stand  one  superior,  two  inferior,  and  two  lateral,  in  the  last-named 
case  (Fig.  282),  and  one  inferior,  two  superior,  and  two  lateral,  in 
the  former  (Fig.  281).  In  terminal  flowers  (401),  the  position  of 
parts  in  respect  to  the  uppermost  leaves  or  bracts  should  be  noted. 

Sect.  IV.     The  Various  Modifications  of  the  Flower. 

445.  The  complete  and  symmetrical  flowers,  with  all  their  or- 
gans in  the  most  normal  state,  that  have  now  been  considered,  will 
serve  as  the  type  or  pattern,  with  which  we  may  compare  the 
almost  numberless  variety  of  forms  which  blossoms  exhibit,  and 
note  the  character  of  the  differences  observed.  We  proceed  upon 
the  supposition  that  all  flowers  are  formed  upon  one  comprehen- 
sive plan,  —  a  plan  essentially  consonant  with  that  of  the  stem  or 


FIG.  280.  Diagram  of  a  Cruciferous  flower  (Erysimum);  a,  the  axis  of  inflorescence.  (The 
bract  is  abortive  in  this,  as  in  most  plants  of  this  family.) 

FIG.  231.  Diagram  of  the  flower  of  a  Rhus,  with  the  axis,  a,  and  the  bract,  i,  to  show  the 
relative  position  of  parts. 

FIG.  282,    Diagram  of  a  flower  of  the  Pulse  tribe,  with  a,  the  axis,  and  b,  the  bract. 


ITS    VARIOUS    MODIFICATIONS.  245 

branch,  of  which  we  have  shown  the  flower  to  be  a  modified  con- 
tinuation, —  SO  that  in  the  flower  we  are  to  expect  no  organs  other 
than  those  that,  whatever  their  form  and  office,  answer  either  to 
the  axis  or  to  the  leaves,  or,  in  other  words,  to  phytons  (230) ;  so 
that  the  differences  between  one  flower  and  another  are  to  be  ex- 
plained as  special  deviations  from,  or  circumstantial  variations  of, 
one  fundamental  plan,  —  variations  for  the  most  part  similar  or 
analogous  to  those  which  are  known  to  occur  in  the  organs  of  veg- 
etation themselves.  Having  assumed  the  type  which  represents 
our  conception  of  the  most  complete,  and  at  the  same  time  the 
simplest  flower,  we  apply  it  to  all  the  cases  which  present  them- 
selves ;  and  especially  to  the  elucidation  of  those  blossoms  in 
which  the  structure  and  symmetry  are  masked  or  obscured ;  where, 
like  the  disenchanting  spear  of  Ithuriel,  its  application  at  once  re- 
veals the  real  character  of  the  most  disguised  and  complicated 
forms  of  structure. 

446.  Our  pattern  flower  consists  of  four  circles,  one  of  each 
kind  of  floral  organ,  and  of  an  equal  number  of  parts,  successively 
alternating  with  one  another.  It  is  complete^  having  both  calyx 
and  corolla,  as  well  as  stamens  and  pistils  (416) ;  symmetrical^ 
having  an  equal  number  of  parts  in  each  whorl  (436) ;  regular^  in 
having  the  different  members  of  each  circle  all  alike  in  size  and 
shape  ;  it  has  but  one  circle  of  the  same  kind  of  organs ;  and 
moreover  all  the  parts  are  distinct  or  unconnected,  so  as  to  exhibit 
their  separate  origin  from  the  axis  or  receptacle  of  the  flower.  Our 
type  may  be  presented  under  either  of  the  four  numerical  forms 
which  have  been  illustrated.  That  is,  its  circles  may  consist  of 
parts  in  twos  (when  it  is  binary  or  dimerous)^  ihrees  {ternary  or 
trimerous),  fours  {quaternary  or  tetramerous),  or  fives  {quinary  or 
pentamerous) .  The  first  of  these  is  the  least  common  ;  the  trime- 
rous  and  the  pentamerous  far  the  most  so.  The  last  is  restricted  to 
Dicotyledonous  plants,  where  five  is  the  prevailing  number ;  while 
the  trimerous  flower  largely  prevails  in  Monocotyledonous  plants, 
although  by  no  means  wanting  in  the  Dicotyledonous  class,  from 
which  Fig.  277  is  taken. 

447.  The  principal  deviations  from  the  perfectly  normal  or  pat- 
tern flower  may  be  classified  as  follows.    They  arise,  either  from,  — 

1st.  The  production  of  one  or  more  additional  circles  of  one  or 
more  of  the  floral  organs  {regular  multiplication  or  augmentation) : 
2d.  The  production  of  a  pair  or  a  cluster  of  organs  where  there 
21* 


246  THE    FLOWEE. 

should  normally  be  but  one,  that  is,  the  multiplication  of  an  organ- 

by  division  {abnormal  multiplication^  also  termed  deduplication  or 

chorisis) : 

3d.  The  union  of  the  members  of  the  same  circle  {coalescence) : 
4th.  The  union  of  adjacent  parts  of  different  circles  {adnation) : 
5th.  The  unequal  growth  or  unequal  union  of  different  parts  of 

the  same  circle  {irregularity)  :  or, 

6lh.  The  non-production  or  abortion  of  some  parts  of  a  circle, 

or  of  one  or  more  complete  circles  {suppression  of  abortion). 
7th.  To  which  may  be  added,  the  abnormal  development  of  the 

receptacle  or  axis  of  the  flower. 

448.  Some  of  these  deviations  obscure  more  or  less  the  symmet- 
rical structure  of  the  flower ;  others  merely  render  it  irregular, 
or  disguise  the  real  origin  or  the  number  of  parts.  These  devi- 
ations, moreover,  are  seldom  single ;  but  two,  three,  or  more  of 
them  frequently  coexist,  so  as  to  realize  almost  every  conceivable 
variation. 

449.  Several  of  these  kinds  of  deviation  may  often  be  observed 
even  in  the  same  natural  family  of  plants,  where  it  cannot  be 
doubted  that  the  blossoms  are  constructed  on  the  same  general  plan 
in  all  the  species.     Even  in  the  family  Crassulacese,  for  example, 

where  the  flowers  are  remarkably  symmetrical, 
^^  and  from  which  our  pattern  flowers.  Fig.  256 

and  277,  are  derived,  a  considerable  number  of 
these  diversities  are  to  be  met  with.  In  Cras- 
sula,  we  have  the  completely  symmetrical  and 
simple  pentamerous  flower  (Fig.  283,  284), 
viz.  with  a  calyx  of  five  sepals,  a  corolla  of 
five  petals  alternate  with  the  former,  an  andrce- 
cium  (418)  of  five  stamens  alternating  with  the 
petals,  and  a  gynsecium  (419)  of  five  pistils, 
which  are  alternate  with  the  stamens  ;  and  all 
the  parts  are  regular  and  symmetrical,  and  also 
distinct  and  free  from  each  other ;  except  that 
the  sepals  are  somewhat  united  at  the  base,  and 
the  petals  and  stamens  slightly  connected  with 
the  inside  of  the  calyx,  instead  of  manifestly 
arising  from  the  receptacle  or  axis,  just  beneath  the  pistils.  Five 
is  the  prevailing  or  normal  number  in  this  family.     Nevertheless, 

FIG.  283.    Flower  ofaCrassula.    284.  Cross-section  of  the  bud. 


ITS   VARIOUS    MODIFICATIONS. 


247 


in  the  related  genus  Tillsea,  most  of  the  species,  like  ours  of  the 
United  States,  have  their  parts  in  fours,  but  are  otherwise  similar, 
and  one  common  European  species  has  its  parts  in  threes  (Fig. 
277) :  that  is,  one  or  two  members  are  left  out  of  each  circle, 
which  of  course  does  not  interfere  with  the  symmetry  of  the  blos- 
som. So  in  the  more  conspicuous  genus  Sedum  (the  Stonecrop, 
Live-for-ever,  Orpine,  &c.)  some  species  are  5-merous,  others 
4-merous,  and  several,  like  our  S.  ternatum,  have  the  first  blossom 
5-merous  but  all  the  rest  on  the  same  plant  4-merous.  But  Sedum 
also  illustrates  the  case  of  regular  augmentation  (447,  1st)  in  its 
androecium,  which  consists  of  twice  as  many  stamens  as  there  are 
members  in  the  other  parts ;  that  is  an  additional  circle  of  stamens 
is  introduced  (Fig.  285,  286),  the 
members  of  which  may  be  distin- 
guished by  being  shorter  or  a  little 
later  than  those  of  the  primary  circle, 
and  also  more  definitely  by  their  al- 
ternation with  the  primary,  which 
brings  them  directly  opposite  the  pet- 
als. A  third  genus  (Rochea)  exhibits 
the  same  5-merous  and  normal  flower 
as  Crassula,  except  that  the  contigu- 
ous edges  of  the  petals  slightly  cohere 
about  half  their  length,  although  a 
little  force  suffices  to  separate  them : 
in  another  (Grammanthes,  Fig.  287), 
the  petals  are  firmly  united  into  a 
tube  for  more  than  half  their  length,  and  so  are  the  sepals  likewise  ; 
presenting,  therefore,  the  third  of  the  deviations  above  enumer- 
ated (447).  Next,  the  allied  genus  Cotyledon  (Fig.  288)  exhibits 
in  the  same  flower  both  this  last  case  of  the  coalescence  of  similar 
parts  in  its  floral  envelopes,  and  an  additional  circle  of  stamens,  as 
in  Sedum.  It  likewise  presents  the  next  order  of  deviations,  in  the 
adnation  of  the  base  of  its  stamens  to  the  base  of  the  corolla,  out 
of  which  they  apparently  arise,  as  is  seen  in  Fig.  289,  where  the 
corolla  is  laid  open  and  displayed.  The  pistils,  although  ordinarily 
exhibiting  a  strong  tendency  to  unite,  are  perfectly  distinct  in  all 
these  cases,  and  indeed  throughout  the  order,  with  two  exceptions ; 
one  of  which  is  seen  in  Penthorum,  where  the  five  ovaries  (Fig. 

FIG.  285.    Flower  of  a  Sedum.    286.  Crosa-seclion  of  the  bud. 


248 


THE    FLOWER. 


290)  are  united  below  into  a  solid  body,  while  their  sunnmits,  as 
well  as  the  styles,  are  separate.  The  same  plant  also  furnishes  an 
example  of  the  non-production  (or  suppression)  of  one  whorl  of 
organs,  that  of  the  petals ;  which,  although  said  to  exist  in  some 
specimens,  are  ordinarily  wanting  altogether.  Another  instance  of 
increase  in  the  number  of  parts  occurs  in  the  Houseleek  (Semper- 
vivum),  in  which  the  sepals,  petals,  and  pistils  vary  in  different 
species  from  six  to  twenty,  and  the  stamens  from  twelve  to  forty. 


450.  Some  illustrations  of  the  principal  diversities  of  the  flower, 
as  classified  above  (447),  may  be  drawn  at  random  from  different 
families  of  plants ;  and  most  of  the  technical  terms  necessarily 
employed  in  describing  these  modifications  may  be  introduced,  and 
concisely  defined,  as  we  proceed.  The  multiplication  of  parts  is 
usually  in  consequence  of  the 

451.  Augmentation  of  the  Floral  Circles.  An  increased  number  of 
circles  or  parts  of  all  the  floral  organs  occurs  in  the  Magnolia 
Family ;  where  the  floral  envelopes  occupy  three  or  four  rows,  of 
three  leaves  in  each,  to  be  divided  between  the  calyx  and  corolla, 
while  the  stamens  and  pistils  are  very  numerous,  and  compactly 
arranged  on  the  elongated  receptacle.  The  Custard-Apple  Fami- 
ly, which  is  much  like  the  last,  has  also  two  circles  in  the  corolla, 
three  petals  in  each,  a  great  increase  in  the  number  of  stamens, 
and,  in  our  Papaw  (see  Ord.  Anonaceae),  sometimes  only  one  circle 
of  pistils,  viz.  3,  sometimes  twice,  thrice,  or  as  many  as  five  times 


3.  The  corolla  laid  open,  showing  the  two  rows  of 


FIG.  287,    Flower  of  Grammanthes. 

FIG.  288.    Flower  of  a  Cotyledon, 
stamens  inserted  into  it. 

FIG.  290.    The  five  pistils  of  Penthorum  united,  so  as  to  form  a  connpound  ovary.    291.  A 
cross-section  of  the  same. 


AUGMENTATION,    OR    REGULAR    MULTIPLICATION.  249 

that  number.  The  Water-Lily,  likewise,  has  all  its  parts  increased 
(Fig.  265),  the  floral  envelopes  and  the  stamens  especially  occu- 
pying a  great  number  of  rows  ;  and  the  pistils  are  likewise  numer- 
ous ;  although  their  number  is  disguised  by  a  combination,  to  be 
hereafter  explained.  When  the  sepals,  petals,  or  other  parts  of 
the  flower  are  too  numerous  to  be  readily  counted,  or  are  even 
more  than  twelve,  especially  when  the  number  is  inconstant,  as  it 
commonly  is  in  such  cases,  they  are  said  to  be  indefinite ;  and  a 
flower  with  numerous  stamens  is  also  termed  polyandrous. 

452.  When  such  multiplication  of  the  floral  circles  is  perfectly 
regular,  the  number  of  the  organs  so  increased  is  a  multiple  of 
that  which  forms  the  basis  of  the  flower ;  but  this  could  scarcely 
be  determined  when  the  numbers  are  large,  as  in  the  stamens  of  a 
Buttercup,  for  example,  nor  is  there  much  constancy  when  the 
whorls  of  any  organ  exceed  three  or  four.  In  such  cases,  the  cir- 
cles usually  appear  to  run  into  a  continuous  spiral,  as  is  plainly 
seen  in  the  cone  of  a  Magnolia  or  of  a  Tulip-tree.  The  doubling 
or  trebling  of  any  or  all  the  floral  circles  does  not  interfere  with 
the  symmetry  of  the  flower  ;  but  it  may  obscure  it  (in  the  stamens 
and  pistils  especially),  by  the  crowding  of  two  or  more  circles  of 
five  members,  for  example,  into  what  appears  like  one  of  ten,  or 
two  trimerous  circles  into  what  appears  like  one  of  six.  The  lat- 
ter case  occurs  in  most  Endogenous  plants. 

453.  The  production  of  additional  floral  circles  may  account  for 
most  cases  of  increase  of  the  normal  number  of  organs,  but  not 
for  all  of  them  ;  unless  through  the  aid  of  hypotheses  that  have  no 
intrinsic  probability,  and  are  unsupported  by  any  clear  analogies 
drawn  from  the  organs  of  vegetation,  which,  it  is  evident,  must 
give  the  rule  in  all  questions  involving  the  morphology,  or  at  least 
the  position,  of  the  floral  organs.  It  must,  we  think,  be  admitted 
that  certain  parts  of  the  blossom  are  sometimes  multiplied  by  fM 
production  of  a  pair  or  a  group  of  organs  which  occupy  the  place 
of  one ;  namely,  by  what  has  been  termed 

454.  Chorisis  or  Beduplication.  The  name  dedouMement  of  Du- 
nal,  which  has  been  translated  deduplication,  literally  means  un- 
lining ;  the  original  hypothesis  being,  that  the  organs  in  question 
unline^  or  tend  to  separate  into  two  or  more  layers,  each  having 
the  same  structure.  We  may  employ  the  word  deduplication,  in 
the  sense  of  the  doubling  or  multiplication  of  the  number  of  parts, 
without  receiving  this  hypothesis  as  to  the  nature  of  the  process, 


250 


THE    FLOWER. 


which  at  best  can  well  apply  only  to  some  special  cases.  The 
word  chorisis  {xatpio-is,  the  act  or  state  of  separation  or  multiplica- 
tion), also  proposed  by  Dunal,  does  not  involve  any  such  assump- 
tion, and  is  accordingly  to  be  preferred.  By  regular  multiplica- 
tion, therefore,  we  mean  the  augmentation  of  the  number  of  organs 
through  the  development  of  additional  circles ;  which  does  not 
alter  the  symmetry  of  the  flower.  By  chorisis  we  denote  the  pro- 
duction of  two  or  more  organs  in  the  place  of  one,  through  the  mul- 
tiplication of  the  leaf  part  of  an  individual  phyton  ;  —  a  case  which 
may  be  compared  with  the  multiplication  of  cells  by  division  (30), 
and  more  directly  with  the  division  of  the  blade  of  a  leaf  into  a 
number  of  separate  blades  or  leaflets.  Chorisis  may  take  place  in 
two  different  ways,  which  are  perhaps  to  be  differently  explained  : 
in  one  case  the  increased  parts  stand  side  by  side ;  in  the  other, 
they  are  situated  one  before  the  other.  Both  cases  must  evidently 
disturb  or  disguise  the  normal  symmetry  of  the  flower. 

455.  Of  the  first  case,  which  may  be  termed  collateral  chorisis, 
we  have  a  good  example  in  the  tetradynamous 
stamens  (519)  of  the  whole  natural  family  Cru- 
ciferae.  Here,  in  a  flower  with  symmetrical  te- 
tramerous  calyx  and  corolla,  we  have  six  stamens ; 
of  which  the  two  lateral  or  shorter  ones  are  al- 
ternate with  the  adjacent  petals,  as  they  normally 
should  be,  while  the  four  are  in  two  pairs,  one 
pair  before  each  remaining  interval  of  the  pet- 
als;  as  is  shown  in  the  annexed  diagram  (Fig. 
292).  That  is,  on  the  anterior  and  on  the  poste- 
rior side  of  the  flower  we  have  two  stamens 
where  there  normally  should  be  but  a  single  one, 
and  where,  indeed,  there  is  but  one  in  some  spe- 
cies of  Cruciferae.  Now  it  occasionally  happens 
that  the  doubling  of  this  stamen  is,  as  it  were,  ar- 
rested before  completion,  so  that  in  place  of  two 
stamens  we  see  a  forked  filament  bearing  a  pair  of 
anthers ;  as  is  usually  the  case  in  several  species 
of  Streptanthus  (Fig.  293).  Here  the  two  sta- 
mens which'  stand  in  the  place  of  one  may  be  compared  with  a 

/ 

FIG.  292.    Diagram  of  a  (tetradynamous)  flower  of  the  order  Cruciferse. 
FIG.  293.    Flower  of  Streptanthus  hyacinthoides,  from  Texas  (the  sepals  and  stamens  re- 
moved), showing  a  forked  or  double  stamen  in  place  of  the  anterior  pair. 


CHORISIS    OR    DEDUPLICATION. 


251 


sessile  compound  leaf  of  two  leaflets.  In  the  related  order  Fuma- 
riacesB,  each  phyton  of 
the  androecium  is  ire- 
hied  in  the  same  man- 
ner. The  circles  of 
the  flower  in  that  order 
are  in  twos  through- 
out, or  dimerous. 
There  is  first,  a  pair 
of  small  scale-like  se- 
pals ;  alternate  with 
these  a  pair  of  petals 
which,  in  Dicentra, 
&c.  (Fig.  294-296), 
are  saccate  or  spurred 
below :  alternate  and 
within  these  there  is  a 
second  pair  of  petals 
(Fig.  297) :  alternate 
with  these  are  two 
clusters  of  three  more 
or  less  united  stamens, 
which  plainly  stand  in  the  place  of  two  single  stamens.  The  ar- 
rangement of  parts  is  shown  in  the  annexed  diagram  (Fig.  298) ; 
where  the  lowest  line  indicates  the  subtending  bract,  and  therefore 
the  anterior  side  of  the  blossom ;  the  two  short  lines  in  the  same  plane 
represent  the  sepals ;  the  two  next  within, 
the  lateral  and  exterior  petals ;  those  al' 
ternate  and  within  these,  the  inner  circle 
of  petals  ;  and  alternate  with  these  are  the 
anthers  of  the  two  stamen-clusters.  The 
centre  is  occupied  by  a  section  of  the  pis- 
til, which,  as  will  hereafter  be  shown,  con- 
sists of  two  united.  The  three  stamens 
are  lightly  connected  in  Dicentra  (Fig.  296) ;  but  in  Corydalis  and 


FIG.  294.  Dicentra  Cucullaria  (Dutchman'a-breeches)  with  its  kind  of  bulb,  a  leaf,  and  a 
scape  in  flower  ;  reduced  in  size  295.  A  flower  of  the  natural  size.  296.  The  same,  with  the 
parts  separated,  except  the  sepals,  one  of  which  is  seen  at  the  base  of  the  pistil.  297.  The  inner 
pair  of  petals,  with  their  tips  coherent. 

FIG.  298.  Diagram  (cross-section)  of  the  similar  flower  of  Adlumia.  299.  One  of  the  sta- 
mens incresised  into  three  by  chorisis  (the  lower  part  of  the  common  filament  is  cut  away). 


252 


THE    FLOWER. 


Adlumia  there  is  only  one  strap-shaped  filament  on  each  side, 
which  is  three-forked  at  the  tip,  each  fork  bearing  an  anther.  One 
of  these  trebled  stamens  is  shown  in  Fig.  299. 

456.  We  have  a  similar  case  in  some  Hypericums  and  in  EIo- 
dea  (Fig.  300),  except  that  in  these,  while  the  floral  envelopes  are 

5-merous,  the  circles  within  them  are 
commonly  3-merous.  The  three 
members  of  the  androecium  are  nor- 
mally placed,  alternating  with  the 
three  members  of  the  gynsecium  with- 
in, and  without  with  three  glands, 
which  probably  replace  an  exterior 
circle  of  stamens;  but  each  member 
as  it  developed  has  divided  above  in- 
to three  stamens  (Fig.  301) ;  each  anther  of  which  may  be  viewed 
as  homologous  with  a  leaflet  of  a  trifoliolate  leaf  (289).  In  the  same 
way  are  the  false  filaments  placed  between  the  petals  and  the  real 
stamens  of  Parnassia,  partly  divided  into  three  in  our  P.  Caroliniana 
(Fig.  305),  or  into  from  9  to  15  shorter  glandular  lobes  in  P.  pa- 
lustris.  So  each  cluster  of  numerous  stamens  of  the  polyandrous 
species  of  Hypericum  (vsee  Ord.  Hypericacese)  doubtless  arises 
from  the  repeated  chorisis  of  a  single  phyton,  and  is  therefore  anal- 
ogous to  a  decompound  leaf.  The  actual  development  of  such  a 
cluster  from  a  small  protuberance,  which  in  the  forming  flower-bud 
stands  in  the  place  of  a  single  phyton,  and  its  repeated  forkings 
as  it  grows,  have  been  traced  by  Duchatre,  particularly  in  Malva- 
ceous  plants. 

457.  Thus  far  we  are  sustained  by  a  clear  analogy  in  the  or- 
gans of  vegetation.  As  the  leaf  frequently  developes  in  the  form 
of  a  lobed,  divided,  or  compound  leaf,  that  is,  as  a  cluster  of  par- 
tially or  completely  distinct  organs  from  a  common  base,  so  may 
the  stamen,  or  even  the  pistil,  become  compound  as  it  grows,  and 
give  rise  to  a  cluster,  instead  of  completing  its  growth  as  a  solitary 
organ  :  and  it  appears  that  the  organogeny  is  strikingly  similar  in 
the  two  cases.  Nor  is  it  very  unusual  for  petals  to  become  divided 
or  deeply  lobed  in  the  same  manner ;  as,  for  example,  those  of 
Mignonette.  In  many  cases,  however,  the  multiplication  takes 
place  in  the  opposite  plane,  so  that  the  parts  are  situated  one  be- 


FIG.  300.    Diagram  (cross-section)  of  a  flower  of  Elodea  Virginica.    301.  One  of  the  three 
stamen-clusters,  consisting  of  a  trebled  stamen. 


CHORISIS    OR    DEDUPLICATION. 


253 


fore  the  other ;  —  an  arrangement  which  is  not  known  to  occur  in 
the  leaflets  of  any  compound  leaf. 

458.  Some  examples  of  this  vertical  or  transverse  chorisis  may- 
be adduced  before  we  essay  to  explain  them.     A 

common  case  is  that  of  the  crown,  or  small  and 

mostly  two-lobed  appendage  on  the  inside  of  the 

blade  of  the  petals  of  Silene  (Fig.  302)  and  of 

many  other  Caryophyllaceous  plants.      This  is 

more  like  a  case  of  real  dedoublement  or  unlining, 

a  partial  separation  of  an  inner  lamella  from  the 

outer,  and  perhaps  may  be  so  viewed.  The  sta- 
mens sometimes  bear  a  similar  and  more  striking 

appendage,  as  in  Larrea  for  example  (Fig.  303), 

and  most  other  plants  of  the  Guaiacum  Family  ;  also  in  the  Dodder 
(Cuscuta,  Ord.  Convolvulacese).  Let  it  be  noted  that 
in  these  cases  the  appendage  occupies  the  inner  side 
of  the  petal  or  stamen,  and  that  it  is  often  two-lpbed. 
Again,  before  each  petal  of  Parnassia  (Fig.  305),  al- 
though slightly  if  at  all  united  with  it,  is  found  a  body 
which  in  P.  palustris  is  somewhat  petal-like,  with  a  con- 
siderable number  of  lobes,  and  in  P.  Caroliniana  is  di- 
vided almost  to  the  base  into  three  lobes,  which  look 

much  like  abortive  stamens.     The  true  stamineal  circle,  however, 

occupies  its  proper  place 

within    these    ambiguous 

bodies,  alternate  with  the 

petals.     We  cannot  doubt 

that  the  former  are  of  the 

same  nature  as  the  scale 

of  the  stamens  in  Larrea, 

and  the  crown  of  the  pet- 
als of  Silene. 

459.  It  may  also  be 
noticed,  that,  while  in  col- 
lateral chorisis  the  in- 
creased parts  are  usually  all  of  the  same  nature,  like  so  many  sim- 


FIG.  302.    A  petal  of  Silene  Pennsylvanica,  with  its  croion  or  appendage. 

FIG.  303.  A  stamen  of  Larrea  Mexicana,  with  a  scale-like  appendage  cohering  with  its 
base  on  the  inner  side. 

FIG.  304.  Diagram  (cross-section)  of  the  flower  of  Parnassia  Caroliniana.  305.  A  petal, 
with  the  appendage  that  stands  before  it. 

22 


254  THE    FLOWER. 

ilar  leaflets  of  a  compound  leaf,  in  what  is  called  transverse  chori- 
sis  there  is  seldom  if  ever  such  a  division  or  ramification  into 
homogeneous  parts ;  but  the  original  organ  remains,  as  it  were,  in- 
tact and  unmodified,  while  it  bears  an  appendage  of  some  different 
appearance  or  function  on  its  inner  face,  or  at  its  base  on  that  side. 
Thus  the  stamens  of  Larrea,  &c.,  bear  a  scale-like  appendage  ;  the 
petals  of  Sapindus,  Cardiospermum,  &c.,  a  petaloid  scale  quite 
unlike  the  original  petal ;  the  petals  of  Parnassia,  a  clust^  of  bod- 
ies resembling  sterile  filaments  united  below.  In  a  still  greater 
number  of  instances,  the  accession  to  the  petal  consists  of  a  real 
stamen  placed  before  it,  and  often  more  or 
less  united  with  its  base,  as  in  the  whole 
Buckthorn  Family  (Fig.  315),  and  in  the 
Byttneriaceae  ;  or  of  a  cluster  of  stamens, 
as  in  the  Mallow  Family,  and  indistinctly  in 
most  European  Lindens,  or  of  such  a  cluster 
with  a  petal-like  scale  in  the  midst,  as  in  the 
American  Lindens  (Ord.  Tiliacese,  Fig.  306). 
In  the  first-named  cases,  the  accessory  organ  developes  entire  and 
simple  ;  in  the  latter,  it  is  multiplied  by  collateral  chorisis.* 

460.  A  most  able  writer  in  a  recent  number  of  the  Journal  of 
Botany,  (with  whom  we  entirely  accord  as  to  the  nature  of  collat- 
eral chorisis,)  "  being  totally  at  a  loss  to  find  any  thing  analogous  in 
the  ordinary  stem-leaves  "  to  this  transverse  or  vertical  multiplica- 
tion of  parts,  inclines  to  consider  such  appendages  as  those  of  the 
petals  of  Silene,  Sapindus,  Ranunculus,  &c.,  as  deformed  glands, 
and  the  stamens  thus  situated,  whether  singly  or  in  clusters,  as  de- 
velopments of  new  parts  in  the  axil  of  the  petals,  &c.t  It  appears 
to  us,  however,  that  the  leaves  do  furnish  the  proper  analogue  of 
these  appendages  (especially  those  of  Fig.  302,  303,  305,  and  the 

*  For  illustrations,  and  more  detailed  explanation  of  these  points,  the  stu- 
dent is  referred  to  the  figures  and  text  of  The  Genera  of  the  United  States  Flo- 
ra Illustrated,  especially  to  Vol.  2.  The  opposition  of  the  exterior  circle  of 
stamens  to  the  petals  in  Geranium,  &c.,  we  explain  in  a  different  way. 

t  Namely,  in  Hooker's  Journal  of  Botany  and  Kew  Garden  Miscellany,  Dec, 
1849,  p.  360.  —  The  morphology  of  true  glands  is  still  obscure,  notwithstand- 
ing the  interesting  light  that  is  thrown  upon  them  in  the  article  here  referred 
to ;  and  stipules  often  tend  to  assume  the  glandular  character. 

I 
FIG.  306.    Diagram  (cross-section)  of  the  unopened  flower  of  the  American  Linden,  to  show 
the  scale  and  the  cluster  of  stamens  before  each  petal. 


CHORISIS    OR   DEDUPLICATION.  255 

petaloid  scales  of  Sapindacese)  in  the  ligule  of  Grasses  (298),  and 
the  stipules  (304).  The  former  occupies  exactly  the  same  posi- 
tion. The  latter  form  an  essential  part  of  the  leaf  (259),  and  usu- 
ally develope  in  a  plane  parallel  with  that  of  the  blade,  but  between 
it  and  the  axis,  particularly  when  they  are  of  considerable  size, 
and  serve  as  teguments  of  the  bud,  as,  for  example,  in  Magnolia 
(Fig.  130)  and  Liriodendron.  The  combined  intrapetiolar  stipules 
of  Melianthus,  &c.,  furnish  a  case  in  point,  to  be  compared  with 
the  two-lobed  internal  scale  of  the  stamens  in  Larrea,  the  two- 
cleft  adnate  appendage  of  the  petals  in  Caryophyllese,  Sapindus, 
&c. ;  and  instances  of  cleft  or  appendaged  stipules  may  readily  be 
adduced  to  show  that  such  bodies  are  as  prone  to  multiplication  by 
division  as  other  foliar  parts.  The  supposition  of  a  true  axillary 
origin  of  the  organs  in  question,  therefore,  appears  to  be  needless, 
and  it  would  certainly  introduce  much  complexity  into  the  theory 
of  the  structure  of  the  flower.  Still,  as  the  axillary  branch  must 
begin  with  a  single  phyton,  its  development  may  in  the  flower  be 
restricted  to  one  phyton  (as  in  the  pistillary  leaf  in  the  axil  of  a 
bract  in  Coniferse) ;  thus  giving  a  single  axillary  organ,  which,  if 
it  multiply  at  all  as  it  developes,  may  do  so  by  collateral  chorisis. 
And,  reduced  to  the  simplest  case,  between  the  transverse  division 
of  a  nascent  phyton,  and  the  axillar  production  of  a  second  phyton 
at  an  extremely  early  period  in  the  development  of  that  which 
subtends  it,  there  is  little  assignable  difference.  At  present,  ac- 
cordingly, we  are  of  opinion  that  the  same  generic  name  may 
properly  enough  be  employed  both  for  the  collateral  and  the  verti- 
cal multiplication  of  organs,  where  two  or  more  bodies  occupy  the 
place  of  one,  carefully  distinguishing,  however,  the  two  different 
cases ;  and  also,  that  a  special  term  is  needful  for  discriminating 
without  circumlocution  between  such  multiplication  and  that  by  th^ 
regular  augmentation  of  floral  organs  through  the  development  of 
additional  circles.  Nor  is  a  special  term  the  less  requisite,  at 
least,  in  systematic  botany,  because  we  recognize,  in  one  or  both 
kinds  of  chorisis^  processes  or  modes  of  division  which  are  com- 
mon to  the  floral  organs  and  to  the  foliage.* 


*  We  are  aware  that  Dr.  Lindley  summarily  rejects  the  whole  doctrine  of 
chorisis,  or  any  evolution  of  two  or  more  bodies  in  the  normal  place  of  one, 
however  explained ;  and  for  three  reasons,  which  may  be  cited  from  Introd. 
to  Botany^  1,  p.  333,  with  a  word  of  comment.     "  1.  There  is  no  instance  of 


256  THE    FLOWER. 

461.  The  Coalescence  or  union  of  the  parts  of  the  same  whorl  or 
set  of  organs  is  so  frequent,  that  few  cases  are  to  be  found  in  which 
it  does  not  occur,  to  a  greater  or  less  extent,  in  some  portion  of  the 
flower.  When  the  sepals  are  thus  united  into  a  cup  or  tube,  the 
calyx  is  said  to  be  monosepalous^  or,  more  correctly,  gamosepalous  : 
when  the  petals  are  united,  the  corolla  is  said  to  be  monopetalous,  or 
gamopetalous ;  the  latter  being  the  appropriate  term,  as  it  denotes 
that  the  petals  are  combined  ;  but  the  former  is  in  common  use,  al- 
though strictly  incorrect,  as  it  implies  that  the  corolla  consists  of  a 
single  petal.  The  inappropriate  names,  in  these  cases,  were  given 
long  before  the  structure  was  rightly  understood.  So,  also,  such  a 
calyx  or  corolla  is  said  to  be  entire^  when  the  sepals  or  petals  are 
united  to  their  very  summits  (as  the  corolla  of  Convolvulus,  which 

unlining  [read  chorisis,  which  Dunal,  as  quoted  by  Lindley,  proposes  to  sub- 
stitute] which  may  not  be  as  well  explained  by  the  theory  of  alternation,"  — 
Not  to  mention  other  instances,  how  is  the  andrcEciura  of  Fumariaceae  to  be 
explained  upon  the  theory  of  alternation  ?  If  by  the  hypothesis  still  repro- 
duced in  the  Vegetable  Kingdom,  p.  436,  we  inquire,  What  analogy  war- 
rants the  supposition  that  a  stamen,  or  a  leaf,  may  split  into  halves,  and  the 
halves  unite  each  with  a  different  filament  which  has  an  angular  distance  of 
90  degrees?  —  "  2.  It  is  highly  improbable  and  inconsistent  with  the  simplicity 
of  vegetable  structure,  that  in  the  same  flower  the  multiplication  of  organs 
should  arise  from  two  wholly  different  causes,  viz.  alternation  at  one  time, 
and  unlining  at  another.  3.  As  it  is  known  that  in  some  flowers,  where  the 
law  of  alternation  usually  obtains,  the  organs  are  occasionally  placed  opposite 
each  other,  it  is  necessary  for  the  supporters  of  the  unlining  theory  to  as- 
sume that  in  such  a  flower  a  part  of  the  organs  must  be  alternate  and  a  part 
unlined,  or  at  one  time  be  all  alternate  and  at  another  time  be  all  unlined, 
which  is  entirely  opposed  to  probability  and  sound  philosophy.  See  the  Ca- 
mellias figured  in  the  Elements  of  Botany,  p.  76,  fig.  156,  157,158.''  —  In 
double  Camellias  the  numerous  petals  of  the  rosette  are  in  some  cases  spirally 
alternate,  in  others  placed  opposite  each  other  in  five  or  more  ranks.  Now, 
when  in  the  very  same  species  two  such  different  modes  of  arrangement  oc- 
cur, is  it  not  a  priori  more  probable  that  the  two  arrangements  result  from 
different  causes  and  are  governed  by  essentially  different  laws?  —  "4.  The 
examination  of  the  gradual  development  of  flowers,  the  only  irrefragable  proof 
of  the  real  nature  of  final  structure,  does  not  in  any  degree  show  that  the  sup- 
posed process  of  unlining  has  a  real  existence."  Compare  with  this  the  well- 
stated  abstract  of  Duchatre's  memoir  on  the  Morphology  and  Organogeny  of 
Malvaceae,  which  is  given  in  the  same  work  (Vol.  2,  p.  70,  et  seq.),  and 
which  demonstrates  that  the  stamens  of  the  Malvaceous  flower  appear  and 
multiply  in  a  manner  wholly  conformable  to  the  doctrine  of  chorisis,  as  here 
maintained,  and  hardly  explicable  upon  any  other  theory.  See,  also,  several 
diagrams  of  the  aestivation  of  flowers  of  Malpighiacese,  where  the  petals  ex- 
tend within  the  outer  row  of  stamens. 


COALESCENCE    OF    ITS    ORGANS. 


257 


thus  appears  to  be  one  simple  organ),  or  to  be  toothed,  lohed,  cleft, 
or  parted,  according  to  the  degree  in  which  the  union  is  incom- 
plete ;  this  language  being  employed  just  as  in  the  case  of  the  di- 
visions of  leaves  (281).  When  the  sepals  are  not  united,  the  calyx 
is  said  to  be  polysepalous ;  and  when  the  petals  are  distinct,  the 
corolla  is  said  to  be  polypetalous ;  that  is,  composed  of  several 
petals.  Examples  of  this  union  of  the  parts  of  the  same  circle 
have  already  been  shown,  as  respects  the  calyx  and  corolla  (Fig. 
287),  and  in  the  account  of  what  is  called  the  monopetalous  divis- 
ion of  the  exogenous  natural  orders  further  illustrations  are  given, 
exhibiting  this  union  in  very  different  degrees. 

462.  The  union  of  the  stamens  occurs  in  various  ways.  Some- 
times the  filaments  are  combined,  while  the  anthers  are  distinct. 
When  thus  united  by  their  filaments  into  one  set,  they  are  said  to 
be  monadelphous ;  as  in  the  Lupine,  &c.,  (Fig.  307).  When 
united  by  their  fila- 
ments into  two  sets, 
they  are  diadelphous 
(Fig.  308),  as  in  most 
plants  of  the  Pea  tribe 
(Leguminosae),where 
nine  stamens  form 
one  set  and  the  tenth 
is  solitary ;  and  in 
Dicentra    (Fig.   296, 

299),  where  the  six  stamens  are  equally  combined  in  two  sets. 
When  united  or  arranged  in  three  sets  or  parcels,  they  are  said  to 
be  triadelphous,  as  in  the  common  St.  John's- wort,  or  if  in  several, 
polyadelphous ;  as  in  other  Hypericums,  in  Tilia,  &;c.  In  some  of 
these  instances,  indeed,  the  stamens  of  each  group  have  a  common 
origin,  as  we  suppose  (456)  ;  still,  the  same  terms  are  employed 
in  botanical  description,  under  whatever  theoretical  views.  In 
other  cases,  the  filaments  are  distinct,  or  nearly  so,  and  the  anthers 
united  into  a  ring ;  as  in  the  vast  order  Compositse,  or  class  Syn- 
genesia  of  the  Linnsean  artificial  system  ;  when  the  stamens  are 
said  to  be  syngenesious  (Fig.  309,  310).  Again,  in  Lobelia,  not 
only  are  the  anthers  syngenesious,  but  the  filaments  are  also  com- 

FIG.  307.  Monadelphous  stamens  of  a  Lupine.  308.  Diadelphous  stamens  (9  and  1)  froni  a 
papilionaceous  flower.     Compare  with  the  diagram,  Fig.  2.S2. 

FIG.  309.  Syngenesious  stamens  of  a  flower  of  a  Composita.  310.  The  tube  of  anthers  laid 
open. 

22* 


258 


THE    FLOWER. 


bined  into  a  tube  for  the  greater  part  of  their  length  (see  Ord.  Lo- 
beliacese).     The  same  thing  is  seen  in 
^^^  ^'^  the  Gourd  tribe,  where  the  anthers  are 

sometimes  long  and  sinuous  or  remark- 
ably contorted,  as  well  as  coherent  into 
a  mass  (Fig.  311-313). 

463.  The  union  of  the  pistils  is  still 
more  common  than  that  of  the  stamens. 
It  occurs  in  every  degree,  from  the  par- 
tial combination  of  the  ovaries,  as  in 
Penthorum  (Fig.  290),  &c.,  to  their  com- 
plete union  while  the  styles  remain  dis- 
tinct, as  in  the  St.  John's- wort  (Ord. 
Hypericacea?),  to  the  partial  union  of 
the  latter,  as  in  the  Mallow,  or  to  the 
perfect  union  of  the  styles  also  into  a  single  body,  as  in  Convol- 
vulus. In  some  cases,  the  styles  are  wholly  combined,  while  the 
ovaries  are  only  partially  so ;  and  in  the  Milk- weed,  the  stigmas 
are  united,  while  the  ovaries  are  distinct.  But  the  structure 
of  the  compound  or  syncarpous  pistil  will  require  particular  illus- 
tration farther  on.  When  there  is  no  such  union,  but  the  sev- 
eral organs  of  the  same  circle  are  separate  or  unconnected,  they 
are  said  to  be  distinct. 

464.  The  terms  union^  cohesion,  and  the  like,  must  not  be  un- 
derstood to  imply  (as  they  might,  without  explanation),  that  the 
organs  in  question  were  first  formed  as  distinct  parts,  and  subse- 
quently cohered.  This  is  seldom  the  case.  The  union  is  congen- 
ital ;  the  members  of  a  gamosepalous  calyx,  a  gamopetalous  corol- 
la, a  monadelphous  circle  of  stamens,  or  a  compound  pistil,  were 
developed  in  connection,  and  showed  their  union  from  the  earliest 
period.  The  language  we  use  has  reference  to  our  idea  of  these 
parts,  as  answering  each  to  a  single  leaf.  We  might  more  correctly 
say  that  the  several  leaves  of  the  same  circle  have  failed  to  isolate 
themselves  as  they  grew.     The  same  remark  applies  to  the  case  of 

465.  Adnation,  or  the  union  of  different  circles  of  floral  organs 
with  one  another.  This  may  take  place  in  various  degrees.  It 
presents  the  appearance  of  one  circle  or  set  of  parts  growing  out 


FIG.  311.  Column  of  stamens,  at  once  triadelphous  and  syngenesious,  of  the  Gourd:  the 
floral  envelopes  cut  away.  312.  A  cross-section  of  the  united  anthers,  nearly  the  natural  size. 
313.  A  sinuous  anther  of  the  Melon. 


ADNATION    OF   ITS    ORGANS.  259 

of  another,  as  the  corolla  out  of  the  calyx,  the  stamens  out  of  the 
corolla,  or  all  of  them  out  of  the  pistil ;  and  therefore  disguises  the 
real  origin  of  the  floral  organs  from  the  receptacle  or  axis,  in  suc- 
cessive series,  one  within  or  above  the  other  (42).  In  the  nu- 
merous cases  where  the  real  origin,  or  insertion^  of  the  floral 
organs  is  not  obscured  by  these  cohesions,  but  where  they  are  in 
appearance  as  well  as  in  theory  inserted  on  the  receptacle,  the 
calyx,  corolla,  and  stamens  are  said  to  be  hypogynous^  that  is,  in- 
serted below  the  pistils ;  as  in  the  Buttercup,  the  Magnolia,  in  Cru- 
ciferous flowers  (Fig.  297),  &c.  The  floral  organs  in  such  cases 
are  also  said  to  he  free ;  which  is  the  term  opposed  to  the  adhesion 
of  one  organ  to  another,  as  that  of  distinct  is  to  the  cohesion  of  the 
parts  of  the  same  whorl  or  set  of  organs.  Thus,  the  stamens 
are  said  to  be  distinct^  when  not  united  with  each  other,  and  to  be 
free^  when  they  contract  no  adhesion  to  the  petals,  sepals,  or  pis- 
tils ;  and  the  same  language  is  equally  applied  to  all  the  floral 
organs.  The  word  connate  (born  united)  is  applied  either  to  the 
congenital  union  of  homogeneous  parts  (as  when  we  say  that  the 
two  leaves  of  the  upper  pairs  of  the  Honeysuckle  are  connate,  the 
sepals  or  stamens  are  connate  into  a  tube,  or  the  pistils  into  a  com- 
pound pistil),  or  to  the  coalescence  of  heterogeneous  parts  (as  that 
of  the  petals  with  the  calyx,  or  of  both  with  the  pistil).  But  the 
word  adnate  belongs  to  the  latter  case  only. 

466.  When  heterogeneous  parts  are  adnate,  that  is  congenitally 
adherent  to  each  other,  some  additional  technical  terms  are  ren- 
dered necessary.  Thus  two  words  are  used  as  counterparts  of 
hypogynous  (under  the  pistil),  and  accord  with  different  degrees 
of  adnation,  viz.  perigynous  and  epigynous.  The  petals  and  sta- 
mens, which  almost  always  accompany  each  other,  are  said  to 
be  perigynous  (literally  placed 
around  the  pistil)  when  they  ad- 
here to  the  base  of  the  calyx,  or 
in  botanical  language  are  inserted 
on  it,  either  directly,  or  perhaps 
more  commonly  by  means  of  a 
disk  or  sort  of  common  fleshy 
base,  from  the  upper  surface  or  edge  of  which  they  grow ;  as  in 

FIG.  314.  A  flower  of  Rhamnua  alnifolius,  showing  the  perigynous  disk,  into  the  margin  of 
which  the  petals  and  stamens  are  inserted.  315.  Vertical  section  through  the  calyx  and  the 
fleshy  disk  which  lines  it. 


260  THE    FLOWER. 

the  Cherry,  the  Buckthorn  (Fig.  314,  315),  &c.  The  same  term 
is  often  applied  to  the  calyx  when  it  is  adnate  to  the  base  of  the 
ovary,  in  which  case  it  necessarily  carries  the  petals  and  stamens 
with  it.  Very  frequently  the  calyx  invests  and  coheres  with  the 
whole  surface  of  the  ovary,  so  that  all  the  parts  of  the  flower  seem 
to  grow  out  of  its  summit ;  as  in  the  Honeysuckle,  the  Dogwood, 
(Fig.  240,  a),  the  Valerian,  &;c.  The  organs  which  thus  appar- 
ently arise  from  the  top  of  the  ovary  are  said  to  be  epigynous 
(literally  on  the  pistil)  ;  a  case  of  which  is 
shown  in  Fig.  316.  The  earlier  botanists 
called  the  flower,  or  calyx,  in  such  cases, 
superior,  and  the  ovary  and  fruit,  inferior ; 
and  when  no  such  combination  occurs,  the 
flower,  or  calyx,  &e.,  was  said  to  be  infe- 
rior, and  the  ovary,  superior.  But  these 
terms  are  nearly,  and  should  be  altogether, 
superseded  by  the  equivalent  and  more  ap- 
propriate expressions  of  calyx  adherent  in  the  one  case,  and  calyx 
free  in  the  other ;  or  that  of  ovary  coherent  with  the  calyx,  and 
ovary  free  from  the  calyx,  which  is  the  same  thing  in  other  words. 

467.  The  various  parts  of  the  flower,  thus  consolidated,  may 
separate  into  their  integral  elements  at  the  point  where  they  be- 
come free  from  the  ovary,  as  in  Cornus  (Fig.  240) ;  or  else  re- 
main variously  combined ;  the  calyx  being  frequently  prolonged 
into  a  tube  with  which  the  petals  and  stamens  cohere,  as  in  the 
Evening  Primrose  (Ord.  Onagracese),  where  the  united  sepals 
form  a  long  and  slender  tube,  bearing  the  petals  and  stamens  on 
its  sumhfiit.  In  most  cases,  where  the  corolla  is  gamopetalous,  the 
stamens  continue  their  adhesion  to  it ;  while  in  the  Orchis  Family 
they  are  free  from  the  corolla,  but  adherent  to  the  pistil,  or  gynan- 
drous. 

468.  Irregularity,  from  unequal  development  or  unequal  union. 
The  Pea  tribe  affords  a  familiar  illustration  of  irregular  flowers, 
arising  from  the  unequal  size  and  dissimilar  form  of  the  floral  en- 
velopes ;  especially  of  the  corolla,  which,  from  a  fancied  reserar 
blance  to  a  butterfly  in  the  flower  of  the  Pea,  &c.,  has  been  called 
papilionaceous.     The  petals  of  such  a  corolla  are  distinguished  by 

FIG.  316,  Vertical  section  through  a  flower  of  Aralia  nudicaulis,  showing  the  calyx  adnate 
to  the  whole  surface  of  the  compound  pistil,  on  the  sumnntit  of  which  the  petals  and  stamens 
are  accordingly  inserted. 


ITS    IRREGULARITY. 


261 


separate  names  ;  the  upper  one,  which  is  usually  most  conspicu- 
ous, being  termed  the  vexillum,  standard,  or  banner  (Fig.  318,  a)  ; 
the  two  lateral  (Z>)  are  called  wings  (alee),  and  the  two  lower  (c), 
which  are  usually  somewhat  united  along  their  anterior  edges,  and 


more  or  less  boat-shaped  (Fig.  319),  together  form  the  keel  (cari- 
na). The  sepals,  which  are  coalescent  below  into  a  cup,  are  also 
of  unequal  size  or  somewhat  unequally  united.  But  here  are  all 
the  parts  of  a  symmetrical  pentamerous  calyx  and  corolla,  only 
they  are  irregular  on  account  of  their  unequal  size,  shape,  or  un- 
ion. There  is  a  tendency  to  become  regular,  however,  in  some 
flowers  of  the  same  tribe  ;  this  is  slightly  observable  in  Baptisia 
(Fig.  321),  but  is  more  manifest  in  Cercis  (the  Red-bud  or  Judas- 
tree),  and  most  of  all  in  Cassia  ;  where  the  five  petals  are  separate, 
spreading,  and  almost  alike  in  size  and  form.  The  irregularity  of 
papilionaceous  flowers  likewise  aflfects  the  stamens,  which,  although 
of  symmetrical  number,  viz.  ten,  or  two  circles,  are  in  most  cases 
unequally  diadelpJwus  (462),  nine  of  them  being  united  by  the  cohe- 
sion of  their  filaments  for  the  greater  part  of  their  length,  while  the 


FIG.  317.  A  flowering  branch  of  Lathy  ru3  my  rtifolius.  318.  The  corolla  displayed  :  a,  the 
vexillum  or  standard;  b,  the  alse  or  wings;  c,  the  two  petals  of  the  carina  or  keel.  319.  The 
keel-petals  in  their  natural  situation.  320.  The  stamens  and  pistil,  enlarged ;  the  sheath  of 
filaments  partly  turned  back. 


262 


THE    FLOWER. 


tenth  (the  posterior)  stamen  is  distinct  or  nearly  so  (Fig.  320).     But 

in  Amorpha  (Fig.  323, 
324),  which  belongs  to  the 
same  family,  an  approach 
to  regularity  is  seen  in  this 
respect,  the  ten  stamens 
being  united  barely  at  their 
base  ;  and  there  is  a  com- 
plete return  to  regularity 
in  those  of  Baptisia  (Fig. 
322),  which  are  perfectly 
distinct  or  separate.  An 
example  of  a  different 
sort  of  irregular  blossom  is 
afforded  by  the  Fumitory 
Family,  the  structure  of 
which  has  already  been  explained,  especially  as  to  the  stamens 
(455,  Fig.  296).  The  floral  envelopes  of  Dicentra  are  in  one  view 
regular,  inasmuch  as  the  two  members  of  each  circle  are  alike  : 
but  the  exterior  pair  of  petals  is  very  unlike  the  interior  pair ;  and 
in  Corydalis  and  Fumaria  itself  one  of  the  exterior  petals  is  unlike 
the  other,  rendering  the  blossom  more  conspicuously  and  truly 
irregular.  Here  the  irregularity  is  combined  with  more  or  less 
cohesion  of  the  petals ;  although  this  union,  like  that  of  the  two 
keel-petals  of  a  papilionaceous  flower,  is  not  congenital,  but  occurs 
subsequently  to  the  development  of  the  organs. 

469.  There  are  many  other  forms  of  irregular  polypetalous 
blossoms,  which  we  cannot  here  separately  explain,  such  as  that  of 
Polygala,  and  that  of  the  Larkspur  and  Monkshood,  both  of  which 
are  farther  complicated  by  the  suppression  of  some  organs,  as  well 
as  by  the  irregular  development  of  others. 

470.  Among  gamopetalous  flowers  the  most  common  case  of 
irregularity  is  that  of  what  are  called  bilabiate  (or  two-lipped)  co- 
rollas, which  prevail  in  the  Mint  Family,  and  to  some  extent  in 
several  related  families.  Here  the  irregularity  of  form  does  not 
arise  from  the  suppression  of  some  of  the  petals,  as  might  at  first 


FIG.  321.  Papilionaceous  flower  of  Baptisia.  322.  The  same,  with  the  petals  removed, 
showing  the  ten  distinct  stamens. 

FIG.  323.  Flower  of  Amorpha.  324.  The  same,  with  the  solitary  petal  removed,  showing 
the  slightly  monadelphous  stamens. 


SUPPRESSION    OR   ABORTION.  263 

sight  be  supposed,  but  from  their  unequal   union :   the  upper  lip 
being  formed  by  the  more  extensive  cohesion   of  the  two  upper 
petals  with  each  other  than  with  the  lateral  ones ;  which  in   like 
manner  unite  with  the  lower  petal  to  form  the  lower  lip  (Fig. 
367).     But,  in  some  such  cases,  the  two  upper  petals  do  not  co- 
here with  each  other  as  far  as  they    do  with  the  lateral  ones, 
and,  being  smaller   in  size,   the  corolla   has  the  appearance  of 
wanting  the  upper  lip,  and  shows  a  deep  cleft  in  its  place  ;  as  in 
Teucrium  Canadense  (see  Ord.  Labiatse).     The  flowers  of  Lobelia 
(see  Ord.  Lobeliacese)  exhibit  a  striking  instance  of  a  similar  kind  ; 
the  two  upper  petals  being  united  with  the  lateral  (which  are  still 
further  combined  with  the  lower,  to  form  the  lower  lip),  but  wholly 
unconnected  with  each  other ;   so  that  the  corolla  appears  to  be 
split  down  to  the  base  on  the  upper  side.     The  ligulate  or  strap- 
shaped  corollas  of  Compositse  are  evidently  formed  in  the  same 
way,  as  if  by  the  splitting  down  of  a  tubular  corolla  on  one  side. 
In  the  bilabiate  corolla  of  most  Honeysuckles  (Ord.  Caprifoliacese), 
the  upper  lip  consists  of  four  united  petals  ;  the  lower  of  only  one. 
471.  Suppression  or  Abortion.     A  complete  flower,  as  already  re- 
marked (416),  comprises  four  whorls  or  sets  of  organs;  namely, 
calyx,  corolla,  stamens,  and  pistils :  when  any  of  these  are  want- 
ing, the  flower  is  said  to  be  incomplete.     Deviations  resulting  from 
the  non-production  of  one  or  more  of  the  whorls  are  not  uncom- 
mon, and  may  affect  any  of  the  floral  organs.     The  calyx,  how- 
ever, is  never  wanting  when  the  corolla  is  present,  or  rather,  when 
the  floral  envelopes  consist  of  only  one  whorl  of  leaves,  they  are 
called  calyx^  whatever  be  their  appearance,  texture,  or  color.    For, 
since  the  calyx  is  frequently  delicate  and  petal-like  (in  botanical 
language  ^e^aZoid  or  colored)^  and  the  corolla  sometimes  greenish 
or  leaf-like,  the  only  real  difl^erence  between  the  two  is,  that  the 
calyx  represents  the  outer,  and  the  corolla  the  inner  series ;  and 
even  this  distinction  becomes  more  or  less  arbitrary  when  either, 
or  both,  of  these  organs  consist  of  more  than  one  circle.     The  ap- 
parent obliteration  of  the  calyx  in  some  cases  is  owing  to  the  entire 
cohesion  of  the  tube  with  the  ovary,  and  the  reduction  of  the  free 
portion,  or  limb,  to  an  obscure  ring  or  border,  either   slightly 
toothed  or  entire,  as  in  Aralia  (Fig.  316),  Fedia  (Ord.  Valeriana- 
cese),  &c.      In   Compositse,  the  partially  obliterated  limb  of  the 
calyx,  when  present  at  all,  consists  of  scales,  bristles,  or  a  ring  of 
slender  hairs  (as  in  the  Thistle),  and  receives  the  name  oi pappus. 


264  THE    FLO  WEE. 

472.  The  petals,  however,  are  frequently  absent ;  when  the 
flower  is  said  to  be  apetalous,  as  in  the  Anemone  (Fig.  325),  Clem- 
atis, Caltha,  &c.,  in  the  Crowfoot 
Family,  other  genera  of  which  are 
furnished  with  both  calyx  and  corol- 
la ;  as  in  some  species  of  Buckthorn, 
while  others  bear  petals ;  as  in  our 
Northern  Prickly  Ash*  (Ord.  Zan- 
thoxylacese),  while  the  petals  are 
present  in  the  Southern  species. 
They  are  constantly  wanting  in  a 
large  number  of  families  of  Exoge- 
nous plants,  which  on  this  account 

form  the  division  ApetalcB.  When  the  calyx  is  present  while  the 
corolla  is  wanting,  the  flower  is  said  to  be  monochlamydeous,  that 
is  with  a  perianth  (417)  or  floral  envelope  of  only  one  kind  ;  as  in 
the  cases  above  mentioned.  But  sometimes  both  the  calyx  and 
the  corolla  are  entirely  wanting,  as  in  the  Lizard's-tail  (Ord.  Sau- 
ruracese)  when  the  flowers,  being  destitute  of  floral  envelopes,  are 
termed  achlamydeous.  The  essential  organs  (418)  are  neverthe- 
less present  in  these  cases,  so  that  the  flower  is  perfect  (or  bisex- 
ual)., although  incomplete. 

473.  A  still  further  reduction,  however,  occurs  in  many  plants ; 
where  even  these  essential  organs  are  not  both  present  in  the  same 
flower,  but  the  stamens  disappear  in  some  flowers,  and  the  pistils 
in  others.  Such  flowers  are  said  to  be  diclinous.,  unisexual,  or  sep- 
arated ;  that  which  bears  stamens  only  is  termed  sterile,  or  stami- 
nate.,  and  that  provided  with  pistils  only,  fertile.,  or  pistillate.  This 
separation  of  the  essential  organs  is  very  frequently  met  with 
where  one  or  both  of  the  floral  envelopes  are  present,  as  in  Me- 
nispermum  (Ord.  Menisperraacese)  and  Prickly  Ash  (Ord.  Zan- 
thoxylacese)  ;  but  when  these  are  absent,  it  presents  instances  of 
the  greatest  possible  reduction  of  which  the  flower  is  suscepti- 

*  In  our  Northern  Zanthoxylum  the  raonochlamydeous  perianth  which  is 
present  may,  however,  be  justly  held  to  be  the  corolla,  and  not  the  calyx,  be- 
cause the  five  stamens  alternate  with  it,  just  as  they  do  with  the  undoubted 
petals  of  Z.  Carolinianum  :  in  this  case,  therefore,  we  may  say  that  the  calyx 
and  not  the  corolla  is  suppressed.     See  Gen.  Illustr.,  2,  p.  148,  tab,  156. 

FIG.  325.  Flower  of  Anemone  Pennsylvanica  (apetaloua  or  monochlamydeous). 


SUPPRESSION    OR   ABORTION. 


265 


ble.*  An  example  of  the  kind  is  furnished  by  Ceratiola  (Ord. 
Empetraceae),  the  sterile  flowers  of  which  consist  merely  of  a 
couple  of  stamens  situated  in  the  axil  of  a  bract ;  and  the  fertile,  of 
a  pistil  surrounded 
by  similar  bracts. 
In  the  Willow  (Fig. 
326  -  329),  which 
presents  a  more  fa- 
miliar illustration, 
the  sterile  flowers 
likewise  consist  of 
two  or  three  stamens 
in  the  axil  of  bracts, 
which  form  a  catkin 
(391) ;  and  the  fer- 
tile, of  solitary  pis- 
tils also  subtended 
by  bracts,  and  dis- 
posed likewise  in  a 
catkin.  That  is,  the 
flowers  are  not  only 

wholly  destitute  of  floral  envelopes  (unless  a  little  glandular  scale 
on  the  upper  side  should  be  a  rudimentary  perianth  of  a  single 
piece),  but  in  one  set  of  blossoms  the  stamens  are  also  suppressed, 
and  in  another,  the  pistils.  The  pistillate  flowers  are  reduced  to  a 
single  pistil.  The  stamens  vary  in  number  in  different  species, 
from  two  to  five.  If  there  were  only  one  of  the  latter,  an  instance 
would  be  afforded  of  flowers  reduced,  not  merely  to  one  kind  of 
organ,  but  to  a  single  organ.  Now  there  is  one  species  of  Willow, 
which  appears  to  have  a  solitary  stamen  in  its  staminate  flowers. 


*  Except,  perhaps,  in  what  are  called  neutral  flowers^  such  as  those  which 
occupy  the  margin  of  the  -cymes  of  several  Viburnums  and  Hydrangeas,  or 
even  the  whole  cluster  in  monstrous  states,  as  in  the  Snowball  or  Guelder 
Rose  of  the  gardens  (Viburnum  Opulus),  and  the  cultivated  Hydrangea,  which 
consist  of  floral  envelopes  only,  with  sometimes  mere  rudiments  of  stamens  or 
pistils.  Of  the  same  kind  are  the  neutral  florets  of  Compositae,  such  as  the 
marginal  flowers,  or  rays^  of  the  Sunflower. 

FIG.  32^.  A  catkiQ  of  staminate  flowers  of  Salix  alba.  327.  A  single  staminate  flower  de- 
tached and  enlarged  (the  bract  turned  from  the  eye).  328.  A  pistillate  catkin  of  the  same  spe- 
cies.    329.  A  detached  pistillate  flower,  magnified. 

23 


266 


THE    FLOWER. 


and  has  therefore  been  named  Salix  monandra.  But  on  inspec- 
tion this  seemingly  single  stamen  is  found  to  consist 
of  two  united  quite  to  the  top  (Fig.  330).  Here,  as  in 
many  other  cases,  the  normal  condition  of  the  flower  is 
not  only  much  altered  by  the  suppression  of  some  organs, 
but  disguised  by  the  coalescence  of  those  that  remain. 
The  blossoms  of  the  Birch  are  very  similar,  except  that 
three  pistils,  the  sole  representatives  of  as  many  flowers, 
are  found  under  each  bract  of  the  fertile  catkin. 

474.  When  the  stamens  and  pistils  are  thus  separated,  the  two 
kinds  of  blossoms  may  be  borne,  either  upon  different  points  or 
branches  of  the  same  individual,  or  upon  entirely  different  individ- 
ual plants.  The  flowers  are  said  to  be  monoecious  when  both  kinds 
are  produced  by  the  same  individual  plant ;  as  in  Indian  Corn,  the 
Birch,  the  Oak,  Beech,  Hazel,  Hickory,  &c.  :  and  they  are  called 
dioecious  when  borne  by  different  individuals ;  as  in  the  Willow 
and  Poplar,  the  Sassafras,  the  Prickly  Ash,  the  Hemp,  Hop,  &c. 
In  many  cases,  while  some  of  the  flowers  are  staminate  only,  and 
others  pistillate  only,  a  portion  are  perfect,  the  different  kinds  oc- 
curring either  on  the  same  or  different  individuals ;  as  in  most 
Palms,  in  many  species  of  Maple,  &c.  :  plants  with  such  flowers 
are  said  to  be  polygamous. 

475.  The  term  suppression  in  all  such  cases  merely  denotes 
that  the  parts  in  question  are  wholly  left  out.  It  is  the  non-pro- 
duction of  some  organ  or  set  of  organs  which  forms  a  component 
part  of  our  pattern  plan  of  the  flower,  and  which  is  realized  in  the 
complete  flower.  The  term  abortion,  which  is  often  used  with 
exactly  the  same  meaning,  is  more  properly  applied  to  those  cases 
where  the  organ  is  deformed  or  imperfect  (where  a  sterile  fila- 
ment, for  example,  occupies  the  position  of  a  stamen),  or  where  a 
mere  rudiment  marks  the  place  of  a  non-developed  organ. 

476.  The  suppression  or  abortion  of  a  whole  circle  of  organs  in 
a  symmetrical  flower  does  not  destroy  its  symmetry,  if  we  count 
the  absent  members.  Thus  a  monochlamydeous  flower,  with  a 
single  full  circle  of  stamens,  usually  has  the  latter  placed  opposite 
the  leaves  of  the  perianth,  that  is,  of  the  calyx,  the  corolla  or  in- 
tervening circle,  with  the  members  of  which  it  normally  alternates, 
having  failed  to  appear;  as  in  Comandra  (Ord.  Santalacese),  Che- 

FIG.  330.    A  staminate  flower  of  Salix  purpurea  (or  monandra),  with  the  stamens  coalescent 
(monadelphous  and  syngenesious),  so  as  to  appear  like  a  single  one. 


SUPPRESSION    OR    ABORTION.  267 

nopodium,  and  the  Elm  (whenever  its  blossoms  have  only  one  set 
of  stamens,  Fig.  338). 

477.  But  when,  with  the  abortion  of  the  primary  circle,  say  of  the 
stamens,  we  have  an  augmentation  of  one  or  more  additional  cir- 
cles of  the  same  kind  of  organ,  the  law  of  alternation  appears  to  be 
violated  ;  the  stamens  that  are  present,  or  the  outer  circle  of  them, 
standing  opposite  the  petals  instead  of  alternate  with  them.  It  is 
customary  to  assume  this  explanation  for  all  cases  of  the  opposition 
of  the  stamens  to  the  petals,  whether  in  the  Primrose  Family,  in 
Claytonia,  in  the  Vine  and  Buckthorn,  or  in  Byttneriacese,  &c. : 
but  considerations  which  have  already  been  adduced  indicate  a  dif- 
ferent explanation  for  many  of  them  (459).  It  can  no  longer  be 
deemed  sufficient  to  assume  the  obliteration  of  a  normal  floral  cir- 
cle, and  the  production  of  another  one,  when  no  traces  of  the  for- 
mer are  to  be  detected  and  no  clear  analogy  shown  with  some 
strictly  parallel  and  demonstrable  instance.  But  we  may  confi- 
dently apply  this  view  when  we  find  traces  of  the  obliterated  or 
abortive  organs,  as  in  the  Geranium  Family,  for  example.  The 
pentamerous  flower  of  Geranium  (Ord.  Geraniacese)  exhibits  ten 
stamens  in  two  rows,  distinguished  by  their  different  length,  the 
five  of  the  exterior  circle  being  shorter  than  the  others.  One  set 
of  these  stamens  alternates  with  the  petals,  the  other  is  opposed  to 
them  ;  which  would  appear  to  conform  to  the  law  of  alternation. 
But,  on  closer  examination,  we  see  that  it  is  the  inner  circle  of  sta- 
mens that  alternates  with  the  petals ;  those  of  the  outer  circle 
stand  directly  before  them.  This  is  a  not  uncommon  case  in  di- 
ploslemonous  flowers  (viz.  in  those  which  have  twice  as  many  sta- 
mens as  there  are  petals  or  sepals).  In  this  instance  the  key  to 
the  explanation  of  the  anomaly  is  furnished 
by  the  five  little  bodies,  called  by  the  vague 
and  convenient  name  of  glands,  which  stand 
on  the  receptacle  between  the  petals  and  the 
stamens,  and  regularly  alternate  with  the  for- 
mer. They  accordingly  occupy  the  exact  po- 
sition of  the  original  slamineal  circle  :  where- 
fore, as  situation  is  the  safest  guide  in  deter- 
mining the  nature  of  organs,  we  may  regard  them  as  the  abortive 

FIG.  331.  Diagram  (cross-section)  of  tlie  flower  of  Geranium  maculatum,  exhibiting  the 
relative  position  of  parts,  especially  the  glands  alternate  with  the  petals,  and  the  two  rows  of 
stamens  within  them. 


268  THE    FLOWER. 

rudiments  of  the  five  proper  stamens,  which  here  remain  unde- 
veloped. In  the  annexed  diagram  (Fig.  331)  these  are  accord- 
ingly laid  down  in  the  third  circle,  as  five  small  oval  spots,  slightly 
shaded.  The  actual  stamens  consequently  belong  to  two  aug- 
mented circles,  those  of  the  exterior  and  shorter  set  of  which 
(represented  by  the  larger,  unshaded  figures),  normally  alternating 
with  the  glands,  are  of  course  opposed  to  the  petals,  and  those  of 
the  inner  and  larger  set,  normally  alternating  with  the  preceding, 
necessarily  alternate  with  the  petals^  This  view  is  further  eluci- 
dated by  the  closely  allied  genus  Erodium,  where  all  the  parts  are 
just  the  same,  except  that  the  five  exterior  actual  stamens  are 
shorter  still,  and  are  destitute  of  anthers ;  that  is,  the  disposition  to 
suppression  which  has  caused  the  obliteration  of  the  primary  circle 
of  stamens,  and  somewhat  reduced  the  second  in  Geranium,  has  in 
Erodium  rendered  the  latter  abortive  also,  leaving  those  of  the 
third  row  alone  to  fulfil  their  proper  office.     It  is  just  the  same  in 

the  Flax  Family,  except  that  the 
glands  which  answer  to  the  primary 
suppressed  stamens  are  still  less  con- 
spicuous, and  those  of  the  next  circle 
are  reduced  to  very  small  abortive 
filaments,  or  to  minute  teeth  in  the 
ring  formed  by  the  union  of  all  the 
filaments  into  a  cup  at  the  base,  leaving  five  perfect  stamens,  which, 
though  they  alternate  with  the  petals  indeed,  belong  to  a  third  cir- 
cle. (Fig,  332,  333.)  In  a  few  species  of  Flax,  the  second  circle 
of  stamens  is  perfectly  obliterated,  so  that  no  vestige  is  to  be  seen. 
478.  The  case  is  different  in  the  Buckthorn  Family  and  in  Bytt- 
neriaceae,  (and  probably  in  Claytonia  also,  Fig.  339,)  where  we 
cannot  but  consider  the  stamens  which  alone  appear,  and  stand 
singly  before  the  petals  (with  which  they  are  frequently  connected  at 
the  base),  as  belonging  to  the  corolline  circle  (459).  Here  the  sym- 
metrical alternation  is  interfered  with  first  by  chorisis,  and  then, 
that  process  having  given  an  abnormal  set  of  stamens,  by  the  total 
suppression  of  the  real  stamineal  circle,  as  in  the  Buckthorn  Fam- 
ily, &c.,  or  their  abortion,  and  reduction  to  sterile  rudiments,  as  in 
many  Byttneriacese  ;  while  in  others  the  genuine  circle  of  stamens 

FIG.  332.  Flowerof  Linum  perenne.  333.  Its  stamens  and  pistils  separated:  tlie  glanda 
are  not  represented  :  the  next  circle  is  reduced  to  minute  sterile  filaments  alternating  with  the 
actual  stamens. 


SUPPRESSION    OR   ABORTION. 


269 


appears   as  an   inner   series.      In  the   same  way   we  incline  to 
explain  the  opposition  of  the  stamens 
to  the  petals  in  the  Grape-vine  also         ^^  ^ 

(Fig.  334-336);  inasmuch  as  the 
five  glands  (represented  by  the  small 
shaded  figures  in  the  diagram,  Fig. 
336)  which  alternate  with  the  petals 
clearly  belong  to  a  circle  within  the 
actual  stamens,  while  there  are  no 
vestiges  outside  of  them.  The 
glands,  therefore,  would  seem  to  rep- 
resent the  proper  stamineal  circle,  in 
an  undeveloped  state,  reduced  to 
these  rudiments  or  to  a  lobed  disk. 

479.  The  stamens  of  the  Barberry 
(Ord.  Berberidacese)  are  in  appear- 
ance only,  but  not  really,  opposed  to  the  petals,  and  the  petals 
to  the  sepals.  Here  the  appearance  is  caused,  not  by  the  sup- 
pression, but  by  the  symmetrical  augmentation  of  the  floral 
envelopes  and  of  the  stamens.  The  calyx  consists  of  two  alter- 
nating circles  of  sepals,  three  in  each ;  the  corolla  of  two  circles 
of  petals,  three  in  each ;  the  three  exterior  petals  alternating  as 
they  should  with  the  inner  circle  of  sepals,  and  the  three  interior 
ones  alternating  with  these.  But  when  the  flower  opens,  the  six 
petals,  spreading  apparently  as  one  whorl,  are  necessarily  opposed 
to  the  six  sepals ;  and  the  six  stamens  in  two  circles,  which  are 
still  more  confluent  into  one  whorl,  are  equally  opposed  to  these, 
taken  six  and  six ;  but  they  really  alternate  in  circles  of  threes. 
In  other  words,  decussating  verticils  of  threes  necessarily  form  six 
vertical  ranks  (251,  441).  It  is  just  the  same  in  the  Lily,  Crocus, 
and  most  Monocotyledonous  plants ;  where  the  perianth  is  com- 
posed of  six  leaves  in  two  circles,  and  the  androecium  of  six  sta- 
mens in  two  circles,  giving  a  regular  alternation  in  threes  ;  al- 
though, taken  as  two  6-merous  circles,  we  have  a  stamen  before 
each  leaf  of  the  perianth. 

480.  The  symmetry  of  the  flower  is  more  frequently  and  seri- 
ously obscured  by  the  suppression  of  a  part  of  the  members  of  the 


FIG.  334.  Flower  of  the  Grape,  casting  its  petals  without  expanding  them.  335.  The  same, 
without  the  petals :  both  show  the  glands  distinctly,  within  the  stamens.  336.  Diagram  of  the 
flower. 

23* 


270 


THE    FLOWER. 


same  circle,  than  from  any  other  kind  of  deviation.  TlTe  tendency 
to  such  obliteration  increases  as  we  advance  towards  the  centre  of 
the  blossom,  owing,  doubtless,  to  the  greater  pressure  exerted  on  the 
central  parts  of  the  bud,  and  the  progressively  diminished  space 
the  organs  have  to  occupy  on  the  conical  receptacle.  So,  while 
the  corolla,  when  present  at  all,  almost  always  consists  of  as  many 
leaves  as  the  calyx,  the  members  of  the  stamineal  circle  or  circles 
are  frequently  fewer  in  number  (although  from  their  form  they  oc- 
cupy much  less  room  than  the  petals),  and  the  pistils  are  still  more 
commonly  fewer,  excepting  where  the  axis  is  prolonged  for  the 
reception  of  numerous  spiral  cycles.  Thus,  the  pistils,  which  pre- 
sent their  typical  number  in  Sedum,  and  all  Crassulaceous  plants 
(Fig.  256,  277,  283-290),  are  reduced  to  two,  or  rarely  three, 
in  the  allied  Saxifragaceous  Family,  while  the  other  floral  circles 
are  in  fives.  So,  in  Aralia  (the  Wild  Sarsaparilla  and  Spikenard), 
the  flowers  are  pentamerous  throughout,  although  the  ovaries  of 
the  five  pistils  are  united  into  one  (Fig.  316) ;  but  in  Panax,  our 
other  genus  of  the  same  family,  they  are  reduced  to  three  in  the 
Ground-nut,  and  to  two  in  the  Ginseng,  as  also  in  all  Umbelliferous 
plants.  Although  the  pistils  are  indefinitely  augmented  in  the 
Kose,  Strawberry,  and  the  greater  part  of  Rosaceous  plants,  or  of 
the  normal  number  five  in  Spirsea,  yet  there  are  only  two  in  Agri- 
monia,  one  or  rarely  two  in  Sanguisorba,  and  uniformly  one  in  the 
Plum  and  Cherry,  although  the  flowers  of  the  whole  order  are 
formed  on  the  pentamerous  or  sometimes  the  tetramerous  plan, 
with  a  strong  tendency  to  augmentation  of  all  the  organs.  And 
the  Pulse  Family  has,  almost  without  exception,  five  members  in  its 
floral  envelopes,  and  ten,  or  two  circles,  in  its  stamens,  but  only  a 
single  pistil  (Fig.  282).  A  flower,  it  may  here  be  added,  is  isom- 
erous  (that  is,  of  equal  members)  when  it  presents  the  same 
number  in  all  its  floral  circles,  —  a  term  therefore  equivalent  with 
symmetrical,  —  and  anisomerous  when  the  number  of  parts  is  dif- 
ferent in  some  of  the  circles. 

481.  As  to  the  stamens,  it  may  be  remarked  that  they  are  usu- 
ally symmetrical  and  regular  when  the  floral  envelopes  are  regu- 
lar (although  the  common  Chickweed  and  the  Maple  are  excep- 
tions to  this  rule) ;  while  they  strongly  tend  to  become  unsymmet- 
rical  by  abortion  or  irregular  (that  is,  of  unequal  size  or  shape) 
when  the  calyx  and  corolla  are  irregular,  or  the  whole  is  oblique 
in  the  bud  ;  the  diflferent  stamens  at  the  time  of  their  development 


SUPPRESSION    OR   ABORTION.  271 

being  therefore  placed  in  unlike  conditions  in  such  cases,  so  as  to 
favor  the  growth  of  some  of  them,  and  to  arrest  or  restrain  others, 
either  by  pressure  or  by  the  abstraction  of  nourishment.  Compare 
in  this  respect  the  more  or  less  irregular  corolla  of  Scrophularia- 
ceous  plants  (see  the  figures  under  Ord.  Scrophulariaceae)  with 
their  stamens.  The  Mullein  (Verbascum)  is  one  of  the  few  gen- 
era of  that  family  which  has  as  many  stamens  as  there  are  pet- 
als in  the  composition  of  its  corolla,  and  sepals  in  its  calyx :  but 
even  here  they  are  unequal,  and  the  posterior  ones  usually  bear 
imperfect  or  deformed  anthers.  In  other  instances,  where  the  five 
stamens  are  all  present,  indeed,  the  posterior  one  is  either  changed 
into  a  bearded  sterile  filament,  as  in  Pentstemon  and  Chelone,  or 
reduced  to  a  mere  rudiment,  as  in  some  Snapdragons ;  or  to  a 
deformed  filament  adherent  to  the  corolla,  and  bearing  a  scale-like 
body  in  place  of  the  anther,  as  in  Scrophularia.  The  four  remain- 
ing perfect  stamens,  in  these  cases,  and  nearly  throughout  the 
order,  are  unequally  developed ;  two  of  them  being  longer  than 
the  remaining  pair ;  as  in  Chelone,  above  cited,  in  Gerardia,  &;c. : 
the  same  thing  is  observed  in  most  plants  of  the  related  orders 
Acanthaceae,  Bignoniaceee,  Orobanchacese,  Verbenacese,  and  La- 
biatse  (which  see).  In  such  cases,  viz.,  where  of  four  two  are 
long  and  two  are  shorter,  the  stamens  are  said  to  be  didynamous. 
Not  unfrequently,  a  further  suppression  takes  place,  and  the  two 
sliorter  of  these  stamens  either  entirely  disappear ;  as  in  the  Sage, 
Monarda,  Lycopus  Virginicus,  &c.,  among  Labiatse,  and  Gratiola 
Virginica,  &c.,  among  the  Scrophulariacese ;  or  else  are  reduced 
to  mere  sterile  filaments,  such  as  those  which  may  commonly  be 
observed  in  Gratiola  aurea,  in  the  Wild  Pennyroyal  (Hedeoma), 
and  in  many  other  Labiate  plants. 

482.  The  obliteration  of  one  or  more  members  of  the  corolla 
follows  the  same  laws.  The  loss  of  a  petal  from  the  circle  is  a 
case  of  irregularity  from  unequal  growth  carried  to  the  greatest 
possible  extent,  or  an  arrest  of  the  development  of  an  organ  from 
an  early  period,  and  we  may  sometimes  trace  the  gradation  in  re- 
lated plants  from  the  diminution  or  dwarfing  of  certain  organs  to 
their  total  suppression.  Thus,  the  papilionaceous  corolla  (468)  of 
Erythrina  herbacea  has  its  five  petals,  but  four  of  them  (all  except 
the  posterior  or  vexillum)  are  small  and  inconspicuous :  in  Amor- 
pha  (Fig.  323),  these  same  four  disappear  altogether,  and  the  pa- 
pilionaceous  corolla  is  reduced  to  its  vexillum  alone.     In  some 


272 


THE    FLOWER. 


cases,  the  obliteration  or  diminution  may  be  attributed  to  local 
pressure  or  obstruction  of  the  light,  acting  uniformly  in  all  instan- 
ces, from  some  constant  cause.  Thus  the  marginal  or  ray  flowers 
of  the  dense  head  in  Compositse  (as  in  the  Aster,  Sunflower,  Cen- 
taurea,  &;c.)  are  not  only  much  larger  than  those  of  the  central  or 
disk  flowers,  which  are  much  pressed  together,  but  their  principal 
development  is  externally.  It  is  the  same  in  the  similar  head  of 
the  Scabious ;  where  the  marginal  corollas  are  not  only  the  larger, 
but  their  exterior  lobes  or  petals  are  much  larger  than  the  inner, 
which  are  dwarfed,  as  it  were,  by  the  pressure  on  that  side.  In 
other  cases,  however,  we  cannot  give  any  such  mechanical  expla- 
nation. In  our  Buckeyes  (Ord.  Sapindacese),  for  example,  the 
whole  five  petals  are  occasionally  present,  as  they  are  uniformly 
in  the  Horsechestnut  (another  species  of  the  same  genus) :  but 
more  commonly  a  vacant  space  marks  the  place  from  which  the 
anterior  petal  has  disappeared.  There  is  also  a  suppression  of  two 
or  three  stamens  out  of  the  two  circles  of  those  organs. 

483.  A  few  diagrams  will  exhibit  some  of  the  stages  of  suppres- 
sion, from  the  complete  and  symmetrical  to  the  most  reduced  con- 
dition of  the  flower.     The  diagram.  Fig.  337,  well  enough  exhibits 

the  ground -plan  of 
a  5-merous  complete 
flower,  symmetrical 
in  all  its  parts,  ex- 
cept that  the  pistils 
are  reduced  from  five 
to  two ;  as  in  SuUi- 
vantia  (Ord.  Saxifragacese).  Fig.  338  is  a  diagram  of  a  similar 
flower,  except  that  the  petals  are  absent  (the  place  they  should  oc- 
cupy is  denoted  by  the  five  dotted  lines) :  this  corresponds  with 
the  Elm  (when  pentandrous),  and  to  Chrysosplenium,  which  is  of 
the  same  family  as  Sullivantia,  only  that  there  the  sepals  and  sta- 
mens are  in  fours,  —  one  being  left  out,  perhaps  we  may  say, 
from  each  circle.  Fig.  339  is  a  ground-plan  of  the  flower  of  the 
common  Claytonia,  or  Spring  Beauty  (Ord.   Portulacacea?),  the 


FIG.  337.    Ground-plan  of  the  flower  of  Sullivantia,  the  united  pistils  reduced  to  two. 

FIG.  338.  Ground-plan  of  a  similar  flower  when  apetalous ;  the  five  doited  lines  indicating 
the  proper  position  of  the  suppressed  petals. 

FIG.  339.  Ground-plan  of  the  flower  of  Claytonia;  the  outer  lines  representing  the  calyx  of 
two  sepals ;  the  next  set  the  corolla  of  five  petals ;  next  are  the  five  stamens  before  the  petals  ; 
and  next  the  ovary,  composed  of  three  parts. 


SUPPRESSION    OR   ABORTION.  273 

ornament  of  our  vernal  woods  ;  —  a  complete  and  regular,  but  re- 
markably unsymmetrical  blossom,  only  two  of  the  four  circles 
having  the  same  number  of  members,  and  one  of  those  (the  sta- 
mens) being  abnormal  in  position.  There  are  only  two  sepals: 
within  these  are  five  petals  :  within  and  opposite  these  are  five 
stamens  ;  so  that  the  primary  stamineal  circle  is  suppressed,  and 
those  present  belong  to  a  second  circle  ;  or,  which  is  more  likely, 
as  they  cohere  at  the  base  with  the  claws  of  the  petals,  they  may 
arise  from  a  chorisis  of  the  petals  themselves :  and  in  the  centre 
there-are  three  pistils  with  their  ovaries  combined  into  one.  Fur- 
ther examples  will  illustrate  those  graver  suppressions  which  render 
the  flower  incomplete,  and  finally  reduce  it  to  a  minimum.  In 
the  Elm  (Ord.  Ulmacese),  the  petals  entirely  disappear,  and  the 
pistils  are  reduced  to  two,  both  of  which  are  abortive  in  a  part  of 
the  flowers,  and  one  always  disappears  in  the  fertile  flowers  dur-- 
ing  the  formation  of  the  fruit.  The  occurrence  of  numerous  cases 
where  parts  that  actually  exist  in  the  pistil  at  the  time  of  flowering 
are  obliterated  in  the  fruit,  justifies  the  use  of  the  term  suppression 
in  the  case  of  parts  which,  though  requisite  in  the  ideal  plan,  are 
left  out  in  the  execution.  Our  Prickly  Ash,  as  already  stated 
(472),  not  only  wants  one  circle  of  floral  envelopes  altogether 
(which,  however,  appear  in  the  species  of  the  Southern  States), 
but,  being  dioecious  (474),  the  stamens  also  disappear  in  all  the 
flowers  of  one  tree,  v^rhile  the  pistils  are  all  abortive  in  those  of 
another  individual.  In  the  Elite  (Ord.  Chenopodiaceee),  where  the 
plan  is  trimerous,  the  petals  and  two  of  the  stamens  are  entirely 


^        ^        o        0         I 


wanting ;  as  the  annexed  diagram  (Fig.  340)  shows.     In  the  Cal- 
litriche  (Ord.  Callitrichacese),  where  the  plan  is  tetramerous,  the 

FIG.  340.    Diagram  of  the  reduced  flower  of  Blitum. 

FIG.  341.  Diagram  of  a  perfect  flower  of  Callitriche,  which  has  no  floral  envelopes,  a  single 
stamen,  and  a  four-celled  pistil. 

FIG.  342.  Diagram  of  the  monoecious  flowers  of  Euphorbia :  a,  the  pistillate  flower,  reduced 
to  a  mere  three-celled  pistil;  and  h,  one  of  the  staminate  flowers  reduced  to  a  single  stamen. 

FIG.  343.  Diagram  of  the  dioecious  flowers  of  the  Willow :  a,  one  of  the  pistillate  flowers 
reduced  to  a  solitary  pistil ;  b,  a  staminate  flower  reduced  to  a  pair  of  stamens. 


274 


THE    FLOWER. 


calyx  and  the  corolla  wholly  disappear,  as  well  as  all  the  stamens 
but  one  (Fig  341) ;  and  even  this  stamen  is  wanting  in  some  of 
the  flowers  on  the  same  stem,  while  other  flowers  consist  of  a  sin- 
gle stamen  only.  This  brings  us  to  a  case  like  that  of  Euphorbia 
(Fig.  344-348,  illustrated  by  the  diagram.  Fig.  342),  the  greatly 
disguised  structure  of  which  would  be  certainly  misapprehended, 
without  special  study.  Nearly  the  furthest  possible  reduction, 
perhaps,  is  seen  in  the  Willow  (Fig.  326-329),  where  the  stami- 
nate  and  pistillate  flowers  are  distributed  to  different  individual 
trees,  the  first  reduced  usually  to  a  pair  of  stamens,  and  the  sec- 
ond to  a  single  pistil.  The  plan  is  represented  in  the  diagram. 
Fig.  343. 

484.  A  full  illustrative  series  of  almost  all  the  kinds  of  deviation 


we  have  mentioned,  but  especially  of  simplification  through  suc- 


FIG.  344.  Flowering  branch  of  Euphorbia  coroUala;  the  lobes  of  the  involucre  resembling  a 
corolla.  345.  Vertical  section  of  an  involucre  (somewhat  enlarged),  showing  a  portion  of  the 
staminale  flowers  surrounding  the  pistillate  flower  (a),  which  in  fruit  is  raised  on  a  slender 
pedicel.  346.  One  of  the  slaminate  flowers  enlarged,  with  its  bract,  a:  b,  the  pedicel,  to  which 
the  single  stamen,  c,  is  attached  by  a  joint ;  there  being  no  trace  of  floral  envelopes.  347. 
Cross-section  of  the  3-pistillate  fruit.  348.  Vertical  section  of  one  of  the  pistils  in  fruit  (the 
two  others  having  fallen  away  from  the  axis),  and  of  the  contained  seed ;  showing  the  embryo 
lengthwise.    349.  A  seed. 


SUPPRESSION    OR   ABORTION.  275 

cessive  suppressions,  might  be  drawn  from  plants  of  the  Euphor- 
biaceous  Family.  Among  them  are  complete  and  perfect  flowers, 
incomplete  and  perfect  flowers,  and  achlamydeous  and  separated 
flowers,  both  monoecious  and  dioecious.  Of  these,  the  staminate 
flowers  in  some  species  are  reduced  to  a  single  stamen,  either  ses- 
sile or  on  a  pedicel,  in  the  axil  of  a  bract ;  and  the  pistillate  either 
to  one  simple  pistil,  or  to  a  compound  pistil  formed  of  two  or  three 
simple  ones  combined.  A  cluster  of  such  axillary  achlamydeous 
flowers,  each  of  a  single  stamen,  collected  at  the  base  of  the  pedi- 
cel of  a  terminal  achlamydeous  pistillate  flower  of  three  coalescent 
pistils,  and  surrounded  by  an  involucre,  —  the  several  leaves  of 
which  are  coalescent  below  into  a  kind  of  cup,  —  forms  the  injlo- 
rescence  of  Euphorbia,  which,  until  explained  by  Mr.  Brown,  was 
mistaken  for  a  single  anomalous  blossom  (Fig.  344-349). 

485.  Abortive  or  unusually  shaped  petals  were  called  Nectaries 
by  the  earlier  botanists,  whether  they  secreted  honey  or  had  a 
glandular  apparatus,  or  not.  This  name  was  applied  to  the  five 
spur-shaped  petals  of  the  Columbine  (Ord.  Ranunculacese),  where 
the  floral  envelopes  are  symmetrical  and  regular,  all  the  petals 
being  alike,  although  of  an  extraordinary  form ;  and  also  to  the 
four  reduced  and  deformed  petals  of  the  unsymmetrical  and  irreg- 
ular flower  of  the  Larkspur,  where  two  of  the  petals  are  spur-shaped 
and  received  into  the  conspicuous  spur  of  the  calyx,  while  the  other 
pair'  are  of  a  different  and  more  normal  form.  In  the 
nearly  related  Aconite,  where  three  of  the  five  petals  are 
obliterated,  the  two  that  remain  (the  nectaries  as  they 
have  been  called)  have  assumed  a  shape  so  remarkable 
(Fig.  350),  that  their  real  nature  could  only  be  recognized 
by  the  position  they  occupy.  Their  appearance  is  rather 
that  of  a  deformed  stamen.  A  sterile  or  deformed  sta- 
men, destitute  of  an  anther,  or  a  body  that  occupies  the 
normal  place  of  a  stamen,  or  is  intermediate  in  appear- 
ance and  situation  between  a  petal  and  a  stamen,  is 
sometimes  called  a  Staminodium  (literally  a  stamen-like 
body).  Staminodia  occur  naturally  and  uniformly  in 
many  plants.  In  cultivated  semi-double  flowers,  such 
transition  states  are  extremely  common,  as  in  the  Lark- 
spurs, Columbines,  &c.,  of  the  gardens. 

FIG.  350.    One  of  the  two  deformed,  stamen-shaped  petals  of  Aconitum  uncinatum. 


276 


THE    FLOWER. 


486.  Abnormal  States  of  the  Receptacle  of  the  flower  remain  to  be 

mentioned,  as  obscuring  more  or  less  the  normal  condition,  or  as 
giving  a  singular  appearance  to  the  blossom.  One  of  the  most 
remarkable  cases  of  the  enlargement  of  the  receptacle  is  that  of  the 
Nelumbium,  where  it  is  dilated  into  a  large  top-shaped  body,  nearly- 
inclosing  the  pistils  in  separate  cavities 
(Fig.  351).  Sometimes  it  is  hollowed  out 
above,  as  well  as  dilated,  as  in  the  Rose, 
where  the  whole  receptacle  expands  into 
an  urn-shaped  disk,  invested  by  the  adnata 
tube  of  the  calyx,  and  bearing  the  petals 
and  stamens  on  its  border  and  the  numer- 
ous pistils  on  the  concave  surface  (Ord. 
RosaceaB).  It  is  much  the  same  in  Caly- 
canthus  (Ord.  Calycanthacese).  In  Gera- 
nium, and  many  allied  plants,  the  receptacle,  which  elevates  the 
ovaries  more  or  less,  is  prolonged  between  them,  and  coheres  with 
their  styles  (Ord.  Geraniacese).  There  is  nearly  a  similar  pro- 
longation in  Euphorbia  (Fig.  348).  Here  there  is  some  develop- 
ment of  the  axis  beyond  the  proper  insertion  of  the  floral  organs. 
Usually  the  floral  internodes  remain  undeveloped  or  extremely 
short,  like  those  of  scaly  leaf-buds  (Fig.  127).  But  now  and  then 
some  of  them  are  elongated  ;  as  in  the  Pink  and  Silene,  where  the 
internode  between  the  calyx  and  the  co- 
rolla forms  a  conspicuous  stalk,  elevating 
the  other  parts  of  the  flower  in  the  tube 
of  the  calyx ;  while  in  many  Gentians 
(Ord.  Gentianacese)  the  internode  above 
the  circle  of  stamens  is  developed,  rais- 
ing the  pod  on  a  stalk  of  its  own.  This 
is  a  common  case  in  the  Gaper  Family  ; 
in  which  the  genus  Gynandropsis  (Fig. 
352)  exhibits  a  remarkable  development 
of  the  whole  receptacle.  It  is  enlarged 
into  a  flattened  disk  where  it  bears  the 
petals,  and  is  then  prolonged  into  a  con- 
spicuous stalk  which  bears  the  stamens  (or  rather,  perhaps,  to 


FIG.  351.    The  enlarged  receptacle  of  Nelumbium. 

FIG.  352,    Flower  of  Gynandropsis,  showing  an  elongated  receptacle,  which  separates  the 
different  sets  of  organs. 


THE    FLORAL    ENVELOPES.  277 

which  the  bases  of  the  stamens  are  adnate),  and  then  into  a  short- 
er and  more  slender  stalk  for  the  pistil ;  thus  separating  the  four 
circles  or  sets  of  organs,  like  so  many  whorls  of  verticillate  leaves. 

487.  The  common  name  for  this  kind  of  stalk,  as  contradis- 
tinguished from  the  pedicel  or  stalk  of  the  flower,  is  the  Stipe  ;  and 
whatever  organ  or  set  of  organs  is  thus  elevated  is  said  to  be  stipi- 
tate.  To  particularize  the  portion  of  the  receptacle  which  is  thus 
developed,  the  stipe  is  termed  the  Anthophore  when  it  appears  just 
above  the  calyx,  and  elevates  the  petals,  stamens,  and  pistil ;  the 
Gonophore,  when  it  supports  only  the  stamens  and  pistils ;  and  the 
Gynophore^  or  Carpophore^  when  it  bears  the  gynsecium  alone. 
The  stalk  which  sometimes  raises  each  pistil  of  the  gynaecium  (as 
in  Coptis  or  the  Goldthread)  is  called  a  Thecaphore.  This,  how- 
ever, does  not  belong  to  the  receptacle  at  all,  but  is  homologous 
with  the  leaf-stalk.* 

Sect.  V.     The  Floral  Envelopes  in  Particular. 

488.  Although  the  various  organs  of  the  flower  have  already 
been  connectedly  considered  under  most  of  their  relations,  there 
yet  remain  some  particular  points  in  respect  to  each  of  them  which 
require  to  be  separately  noticed.  It  will  still  be  most  convenient 
to  treat  of  the  calyx  and  corolla  together,  on  account  of  their  gen- 
eral accordance  in  most  respects. 

489.  Their  Development,  or  Organogeny,  first  requires  a  brief  notice. 

The  flower-bud  is  formed  in  the  same  way  as  the  leaf-bud ;  and 
what  has  been  stated  as  to  the  formation  of  the  leaves  of  the 
branch  (274)  equally  applies  to  the  leaves,  or  envelopes,  of  the 
flower.  The  sepals  are  necessarily  the  earliest  to  appear,  which 
they  do  in  the  form  of  so  many  cellular  tumors  or  nipples,  at  first 
distinct,  inasmuch  as  then  their  tips  only  are  eliminated  from  the 
axis.     Each  one  may  complete  its  development  separately,  in  the 


*  A  few  terms  which  relate  to  the  combination  of  different  kinds  of  flowers 
in  the  same  inflorescence,  or  their  corresponding  separation,  may  here  be  de- 
fined. Thus,  a  head  or  spike  of  flowers  is  said  to  be  homogamous  wlien  all 
its  blossoms  are  alike,  as  in  Eupatorium;  or  heterogamous,  when  it  includes 
two  or  more  kinds,  as  in  the  Sunflower  and  Aster.  It  is  androgynous  when 
it  consists  of  both  staminate  and  pistillate  flowers,  as  the  spikes  of  many- 
Sedges.  When  the  two  kinds  of  flowers  occupy  difl^erent  heads,  whether  on 
the  same  or  two  different  individuals,  they  are  heterocephalous. 

24 


278  THE    FLOWER.  " 

same  manner  as  an  ordinary  leaf,  (only  no  petiole  is  interposed  be- 
tween the  blade  and  the  axis,*)  when  the  sepals  remain  distinct 
(463)  or  unconnected.  Otherwise,  the  lower  and  later-eliminated 
portions  of  the  nascent  organs  of  the  circle  coalesce  as  they  grow 
into  a  ring,  which,  further  developed  in  union,  forms  the  cup  or  tube 
of  the  gamophyllous  calyx :  or,  in  some  cases,  it  would  appear  that 
the  sepals  may  at  first  grow  separately,  and  afterwards,  though 
only  at  a  very  early  period,  coalesce  by  the  cohesion  of  their  con- 
tiguous parts.  The  several  parts  of  an  irregular  calyx  are  at  first 
equal  and  similar ;  the  irregularity  is  established  in  their  subse- 
quent unequal  growth.  The  petals  or  parts  of  the  corolla  originate 
in  the  same  way,  a  little  later  than  the  sepals.  Their  coalescence 
in  the  gamopetalous  corolla,  as  far  as  known,  is  strictly  congenital : 
the  ring  which  forms  its  tube  appearing  nearly  as  early  as  the 
slight,  projections  which  become  its  lobes  and  answer  to  the  sum- 
mits of  the  component  petals.  The  rudiments  of  the  petals  are 
visible  earlier  than  those  of  the  stamens ;  t  but  their  growth  is  at 
first  retarded,  so  that  the  stamens  are  earlier  completed,  and  their 
anthers  surpass  them,  or  often  finish  their  growth,  while  the  petals 
are  still  minute  scales  :  at  length  they  make  a  rapid  growth,  and 
inclose  the  organs  .that  belong  above  or  within  them.  Unlike 
the  sepals  in  this  respect,  the  base  of  the  petal  is  frequently  nar- 
rowed into  a  portion  which  corresponds,  more  or  less  evidently,  to 
the  petiole  (the  claiv),  which,  like  the  petiole,  does  not  appear  until 
some  time  after  the  blade  or  expanded  part ;  the  summit  being  al- 
ways the  earliest  and  the  base  the  latest  portion  formed.  As  the 
envelopes  of  the  flower  grow  and  expand,  those  of  each  circle 
adapt  themselves  to  each  other  in  various  ways,  and  acquire  the 
relative  positions  which  they  occupy  in  the  flower-bud.  Their  ar- 
rangement in  this  state  is  termed 

490.  Their  ^Estivation  or  Prtcfloration.  The  latter  would  be  the 
preferable  term  ;  but  the  former  is  in  common  use  ;  the  word  jEsti- 
vation  (literally  the  summer  state)  having  been  formed  for  the 

*  At  least  the  case  of  a  petiolate  sepal  is  very  rare.  The  sepals  are  rather 
to  be  compared  to  bracts,  which  are  mostly  sessile,  than  to  ordinary  leaves. 

t  When  the  stamens,  or  an  exterior  set  of  them,  originate  by  chorisis  or  de- 
duplication  of  the  petals  (459),  it  appears  from  the  observations  of  Duchatre 
that  the  five  protuberances  which  represent  the  petals  at  their  first  appearance 
divide  transversely,  or  grow  double,  the  inner  half  developing  into  a  stamen 
or  a  cluster  of  stamens,  the  outer  into  the  petal  itself. 


JESTIVATION.  279 

purpose  by  Linnaeus ;  —  for  no  obvious  reason  except  that  he  had 
already  applied  the  name  of  Vernation  (the  spring  state)  to  express 
the  analogous  manner  in  which  leaves  are  disposed  in  the  leaf-bud. 
The  same  terms  are  employed,  and  in  nearly  the  same  way,  in  the 
two  cases,  but  with  some  peculiarities.  As  to  the  disposition  of 
each  leaf  taken  by  itself,  the  corresponding  terms  of  vernation 
(257)  wholly  apply  to  sestivation  ;  and  there  are  no  forms  of  any 
consequence  to  be  added,  perhaps,  except  the  corrugate  or  crum- 
pled, where  each  leaf  is  irregularly  crumpled  or  wrinkled,  longi- 
tudinally or  transversely,  one  or  both,  as  happens  in  the  petals  of 
the  Poppy  and  the  Helianthemum,  —  a  case  that  is  not  met  with  in 
the  foliage  ;  the  indupUcate,  where  the  edges  are  folded  inwards, 
as  those  of  the  sepals  of  Clematis  (Fig.  357),  —  but  this,  as  com- 
pared with  vernation  is  only  a  modification  of  the  involute ;  and 
the  reduplicate,  where  the  margins  are  bent  outwards  instead  of 
inwards,  as  in  the  corolla  of  the  Potato,  —  which  is  a  mere  modifi- 
cation of  the  revolute  in  vernation. 

491.  The  arrangement  in  the  bud  of  the  several  members  of  the 
same  floral  circle  in  respect  to  each  other  is  of  much  importance 
in  systematic  botany,  on  account  of  the  nearly  constant  characters 
that  it  furnishes,  and  still  more  in  structural  botany,  from  the  aid  it 
often  affords  in  determining  the  true  relative  superposition  or  suc- 
cession of  parts  on  the  axis  erf"  the  flower,  by  observing  the  order  in 
which  they  overlie  or  envelope  each  other ;  for  every  enveloping 
part  is  almost  necessarily  external  to,  or  of  lower  insertion  than, 
the  part  enveloped.  The  various  forms  of  sBstivation  that  have 
been  distinguished  by  botanists  may  be  reduced  to  three  essential 
kinds,  namely,  the  imbricalive,  the  contorted  or  convolutive,  and 
the  valvular.* 

492.  Imhricative  aestivation,  in  a  general  sense,  comprises  all 
the  modes  of  disposition  in  which  some  members  of  a  floral  circle 
are  exterior  to  the  others,  and  therefore  overlie  or  inclose  them  in 
the  bud.  This  must  almost  necessarily  occur  wherever  the  parts 
are  inserted  at  distinguishably  diflferent  heights,  and  is  the  natural 
result  of  a  spiral  arrangement.      The   name  is  most  significant 


*  We  should  properly  say  of  the  aestivation  that  it  is  imhricative^  convolu- 
tivCy  valvular,  &c.,  and  of  the  calyx  and  corolla,  or  of  the  sepals,  &c.,  that 
they  are  imbricate,  or  imbricated,  convolute,  valvate,  &c.,  in  aestivation ;  but 
such  precision  of  language  is  seldom  attended  to. 


280  THE    FLOWER. 

when  successive  leaves  are  only  partially  covered  by  the  preced- 
ing, as  in  Fig.  174-  176  ;  here  they  manifestly  break  joints,  or  are 
disposed  like  tiles  or  shingles  on  a  roof,  as  the  term  imbricated  de- 
notes. It  is  therefore  equivalent  to  the  spiral  arrangement,  which 
word  is  sometimes  substituted  for  it  in  aestivation :  and,  on  the 
other  hand,  we  properly  apply  the  term  imbricated  to  any  contin- 
uous succession  of  such  partly  overlying  members,  as  when  we 
say  of  appressed  and  crowded  leaves  that  they  are  imbricated  on 
the  stem,  or  thus  express  the  whole  arrangement  of  the  scales  of 
a  bud  (Fig.  127),  or  a  bulb  (Fig.  141),  or  of  a  catkin  or  cone 
(Fig.  175).  The  alternation  of  the  petals  with  the  sepals,  &c., 
necessarily  makes  the  floral  envelopes  likewise  imbricated  in  the 
bud,  taken  as  a  whole.  But  in  proper  sestivation,  what  we  have  to 
designate  is  the  arrangement  of  the  parts  of  the  same  floral  circle, 
say  the  five  sepals  or  the  five  petals,  in  respect  to  each  other. 

493.  Now  where  the  calyx  or  the  corolla  exhibits  the  character 
of  a  complete  cycle  (439)  or  of  a  part  of  a  cycle  (442)  of  leaves 
with  the  internodes  undeveloped,  that  is,  where  we  may  perceive 
on  close  inspection  that  the  several  members  are  inserted  on  the 
receptacle  at  unequal  heights,  this  will  be  manifested  in  the  bud 
by  the  relative  position  of  these  members  :  the  lower  or  outer  must 
overlie  or  inclose  the  upper  or  inner.  This  is  just  the  case  in  reg- 
ular imbricative  sestivation  ;  where,  of  five  sepals,  for  example  (as 
in  the  diagrams,  Fig.  300,  281),  two  will  be  wholly  exterior  in  the 
bud,  two  wholly  interior,  and  one  intermediate,  namely,  covered  at 
one  edge  by  one  of  the  exterior,  while  its  other  edge  overlies  that  of 
one  of  the  inner  sepals ;  —  which,  on  comparison  with  Fig.  172, 
173,  will  be  found  to  correspond  exactly  with  the  f  or  quincuncial 
arrangement  of  leaves  as  presented  on  a  similar  ground-plan. 
Leaves  No.  1  and  No.  2  are  external ;  No.  3  is  internal  in  respect 
to  these,  but  external  in  respect  to  No,  4,  which  is  two  fifths  of  the 
circumference  distant,  and  more  manifestly  to  No.  5,  which,  being 
separated  by  an  interval  of  two  fifths  from  the  preceding,  com- 
pletes the  cycle,  and  is  overlapped  by  No.  3.  In  this,  the  normal 
and  the  mOst  common  arrangement  in.  the  5-merous  flower,  the 
parts  are  said  to  be  spirally,  or  (with  more  definiteness  as  to  the 
numerical  kind  of  spire)  quincuncially  imbricated  in  sestivation. 

494.  We  have  here  the  advantage  of  being  able  to  number  the 
successive  sepals,  or  petals,  since  the  third  leaf  is  not  only  recog- 
nizable by  its  intermediata  position,  but  also  indicates  the  direction 
in  which  the  spiral  turns,  as  is  shown  in  Fig.  173. 


JESTIVATION.  281 

495.  The  same  regularly  imbricated  arrangement  in  trimerous 
flowers  gives  one  exterior,  one  half  interior  and  half  exterior,  and 
one  interior  member  in  aestivation,  after  the  order 
of  ^  cycles,  as  is  shown  in  the  diagram.  Fig.  353,  /^^^^^ 
both  for  the  calyx  and  corolla;  —  which  compare 
with  Fig.  171,  recollecting  that  the  successive 
cycles  are  superposed  in  the  foliage,  while  the 
floral  circles  alternate.  Regular  imbrication  in 
the  4-merous  flower  gives  two  outer  and  two  inner 

members  in  asstivation  (as  in  the  calyx  of  Cruciferous  blossoms, 
Fig.  280),  on  the  principle  of  two  decussating  pairs  of  leaves 
(439) ;  or  it  may  sometimes  be  referable  to  a  modification  of  some 
alternate  spiral  arrangement. 

496.  The  degree  of  overlapping  depends  upon  the  breadth  of 
the  parts  and  the  state  of  the  bud ;  it  naturally  grows  less  and 
less  as  the  bud  expands  and  is  ready  to  open.  It  is  from  the  full- 
grown  flower-bud,  just  before  anthesis  (or  the  opening  of  the  blos- 
som), that  our  diagrams  are  usually  taken  ;  in  which  the  parts  are 
represented  as  moderately  or  slightly  overlapping.  The  same 
overlapping  carried  to  a  greater  extent  will  cause  the  outer  leaf  to 
envelope  all  the  rest,  and  each  succeeding  one  to  envelope  those 

within  ;  as  shown  in  Fig.  354  from  one  circle 
of  petals  of  a  Magnolia  taken  in  an  early  state 
of  the  bud.  Here  the  mode  is  just  the  same  as 
that  of  Fig.  353.  To  this,  however,  has  not 
improperly  been  applied  the  name  of  convo- 
lute, from  its  similarity  to  the  convolute  verna- 
tion of  the  leaves  of  the  branch  (257),  simi- 
larly rolled  up  one  within  the  other.  But  it  is 
practically  inconvenient,  and  wrong  in  principle,  to  designate  dif- 
ferent degrees  of  the  very  same  mode  by  distinct  names ;  further- 
more, the  next  general  kind  of  aestivation,  when  carried  to  a  high 
degree  of  overlapping,  produces  a  somewhat  similar  result ;  and 
moreover,  it  is  to  this  second  mode,  whatever  be  its  degree,  that 
the  name  of  convolute  is  more  commonly  applied,  in  recent  syste- 
matic botanical  writings. 

497.  There  are  numerous  cases  of  imbricative  restivation,  espe- 

FIG.  353.    Imbricated  sestivation  of  the  calyx  and  the  corolla,  in  a  trimerous  flower. 
FIG.  354.    The  strongly  enveloping  imbricative  asativation  of  the  three  exterior  petals  of 
Magnolia  grandiflora. 

24* 


282  THE    FLOWER. 

cially  in  irregular  flowers,  where  the  overlapping  of  parts  does  not 
altogether  accord  with  what  must  needs  be  their  order  of  succes- 
sion on  the  axis.  In  the  5-merous  calyx  and  corolla  of  all  truly 
papilionaceous  flowers,  for  example,  one  edge  of  the  sepal  or  the 
petal  No.  2  is  placed  under  instead  of  over  the  adjacent  edge  of 
No.  4,  in  consequence  of  which  three,  instead  of  only  one,  of  the 
leaves  have  one  edge  covered  and  the  other  external  ;  as  is  shown 
in  Fig.  282.  Since,  in  the  corolla  of  this  kind  of  blossom,  the  ex- 
terior petal,  here  the  vexillum  (468),  is  the  larger,  and  at  first  em- 
braces all  the  rest  (as  is  seen  in  the  separate  diagram  of  the 
corolla.  Fig.  359),  this  modification  of  imbricative  aestivation  has 
received  the  name  of  vexiUary.  As  nearly  the  same  thing  occurs 
in  the  Violet,  it  is  probably  caused  by  some  slight  dislocation  that 
takes  place  during  the  early  growth  of  organs  in  the  irregular 
blossom,  which  the  study  of  their  development  should  explain.  It 
is  not  restricted  to  irregular  flowers,  however,  but  occurs  as  a  cas- 
ual variation,  or  perhaps  more  frequently  than  the  quincuncial,  in 
the  regular  corolla  of  the  Linden  (as  is  shown  in  Fig.  306).  A 
slight  obliquity  in  the  position  of  the  petal  No.  2,  assumed  at  an 
early  period,  would  account  for  the  whole  anomaly.  That  this 
suggests  the  true  explanation  is  almost  demonstrated  by  the  vary- 
ing aestivation  of  the  corolla  of  the  Linden ;  in  which  the  same 
bunch  of  blossoms  often  furnishes  instances  of  regular  quincuncial 
imbrication,  of  the  modification  here  referred  to,  and  of  the  similar 
disposition  of  the  fifth  petal,  throwing  one  of  its  edges  outwards 
also.  If  the  first  petal  were  also  to  partake  of  this  slight  obliquity, 
the  imbricative  would  be  completely  converted  into  what  is  vari- 
ously named 

498.  The  contorted^  twisted^  or  convolutive  sestivation  (Fig.  360, 
the  corolla,  and  361).  In  this  mode,  the  leaves  of  the  circle  are  all, 
at  least  apparently,  inserted  at  the  same  height,  and  all  occupy  the 
same  relative  position  :  one  edge  of  each,  being  directed  obliquely 
inwards,  is  covered  by  the  adjacent  leaf  on  that  side,  while  the 
other  covers  the  corresponding  margin  of  the  contiguous  leaf  on 
the  other  side.  This  is  owing  to  a  more  or  less  evident  torsion 
or  twisting  of  each  member  on  its  axis  early  in  its  develop- 
ment ;  so  that  the  leaves  of  the  floral  verticil,  instead  of  forming 
arcs  of  a  circle,  or  sides  of  a  polygon  having  for  its  centre  that  of 
the  blossom,  severally  assume  an  oblique  direction,  by  which  one 
edge  is  carried  partly  inward  and  the  other  outward.     This  con- 


ESTIVATION. 


283 


torted  sestivation  is  scarcely  ever  met  with  in  the  calyx,  but  is  very 
common  in  the  corolla.  When  this  obliquity  of  position  is  strong, 
the  petals  themselves  are  usually  oblique,  or  unequal-sided,  from 
the  lesser  growth  of  the  overlapped  side,  which  is  by  no  means  so 
favorably  situated  in  this  respect  as  is  the  free  external  portion,  — 
a  case  of  partial  obliteration  or  dwarfing  from  pressure.  This  is 
well  seen  in  the  petals  of  most  Malvaceous  plants,  to  some  extent  in 
those  of  Geranium,  Flax,  and  Wood-Sorrel,  and  strikingly  in  those 
of  the  St.  John's-wort,  and  in  the  lobes  of  the  corolla  of  the  Peri- 
winkle (Vinca)  and  of  most  other  Apocynaceous  plants.  In  the 
Pink,  however,  and  in  many  other  instances,  the  petals  are  sym- 
metrical, although  strongly  convolute  in  sestivation.  When  the 
petals  are  broad,  this  arrangement  is  frequently  conspicuous  in  the 
fully  expanded  flower,  as  well  as  in  the  bud  (as  in  Fig.  365).  The 
convolution  in  the  bud  is  often  so  great,  that  the  petals  appear  as  if 
strongly  twisted  or  rolled  up  together,  each  being  almost  complete- 
ly overlapped  by  the  preceding,  so  that  they  become  convolute 
nearly  in  the  sense  in  which  the  term  is  used  in  vernation  ;  as  in 
the  Wallflower  (Fig.  360,  361).  Although  there  is  some  diver- 
sity of  usage,  the  terms  convolute  and  contorted  in  aestivation  are 


now  for  the  most  part  employed  interchangeably,  or  nearly  so.    In 


FIG.  355-  363.  Diagrams  of  aestivation.  (When  there  are  two  circles,  the  outer  represents 
the  calyx  and  the  inner  the  corolla.)  355.  Valvate.  356.  Valvale  calyx;  the  corolla  indu- 
plicate  or  nearly  conduplicate.  357.  Involute,  rather  than  induplicate,  sepals  of  Clematis. 
358.  Quincuncially  imbricated;  the  first  leaf  on  the  upper  side.  359.  Vexillary  imbricated 
papilionaceous  corolla.  360.  Imbricated  calyx  of  Wallflower  (two  outer  and  two  inner  sepals), 
and  within  the  strongly  contorted  or  convolute  corolla.  361.  Contorted  or  convolute  corolla, 
with  the  petals  more  expanded.  362.  Plaited  tube  of  the  corolla  of  Campanula.  363.  Plaited 
and  supervolute  corolla  of  Convolvulus. 


284  THE    FLOWER. 

Geranium,  and  in  many  other  cases  (as  in  Fig.  280),  we  find  the 
prevailingly  contorted  or  convolute  aestivation  affecting  casual  tran- 
sitions to  the  imbricative  mode,  corresponding  to  those  already 
mentioned  in  the  foregoing  paragraph. 

499.  The  valvular  or  valvate  aestivation  is  that  in  which  the  parts 
of  a  floral  verticil  are  placed  in  contact,  edge  to  edge,  through- 
out their  whole  length,  without  any  overlapping  (as  in  Fig.  355, 
and  the  calyx  in  Fig.  356).  Here  the  members  of  the  circle  are 
strictly  verticillate,  and  stand  in  an  exact  circle,  no  one  being  in 
the  least  degree  lower  or  exterior.  The  edges  of  the  sepals  or 
petals  in  this  case  are  generally  abrupt,  or  as  thick  as  the  rest  of 
the  organ,  as  is  shown  in  the  calyx  of  the  Linden  (Fig.  306) ;  by 
which  mark  the  valvate  aestivation  may  commonly  be  recognized 
in  the  expanded  flower.  The  several  parts  being  all  developed 
under  precisely  similar  conditions  in  this  and  the  foregoing  modes 
of  aestivation,  these  are  naturally  and  almost  without  exception  re- 
stricted to  regular  flowers  alone. 

500.  By  the  inflexion  of  the  edges,  the  strictly  valvate  aestivation 
passes  by  insensible  gradations  into  the  induplicate  (490),  as  in  the 
calyx  of  some  species  of  Clematis ;  a  mode  which  is  carried  to  a 
maximum  in  some  species  of  Lysimachia  (Fig.  356),  where  the 
two  edges  of  the  same  petal  are  brought  into  contact,  so  as  to  be 
conduplicate.  When  the  induplicate  margins  are  inrolied,  they 
become  involute  (Fig.  357)  in  aestivation.  On  the  contrary,  the 
valvate  calyx  of  many  Malvaceous  plants  and  the  corolla  of  the 
Potato  blossom  have  the  margins  projecting  outwards  into  salient 
ridges,  or  are  reduplicate,  in  aestivation. 

501.  The  tube  of  a  gamopetalous  corolla  occasionally  exhibits 
similar  ridges  or  folds,  whether  salient  (as  in  the  bud  of  some 
Campanulas,  Fig.  362),  or  reentering  (as  in  Stramonium) :  this 
gives  rise  to  the  plicative,  plicate,  or  plaited  modification  of  aesti- 
vation. Where  the  plaits  are  folded  round  each  other,  in  a  convo- 
lutive  manner,  the  aestivation  is  sometimes  termed  supervolutive, 
or  supervolute,  as  in  the  Morning  Glory  (Fig.  363). 

502.  The  spire  in  imbricative  aestivation,  and  the  order  of 
overlapping  in  the  contorted  mode,  may  turn  either  from  left  to 
right,  or  from  right  to  left ;  and  the  direction  is  often  uniform 
through  the  same  genus  or  family,  but  sometimes  diverse  in  difier- 
ent  blossoms  on  the  same  plant.  In  fixing  the  direction,  we  sup- 
pose the  observer  to  stand  before  the  flower-bud.     De  Candolle, 


THE    CALYX.  285 

indeed,  supposes  the  observer  to  occupy  the  centre  of  the  flower, 
which  would  reverse  the  direction  ;  but  the  former  view  is  gener- 
ally adopted.  The  direction  is  frequently  reversed  in  passing  from 
the  calyx  to  the  corolla,  —  sometimes  with  remarkable  uniformity  ; 
while  again  the  two  occur  almost  indifferently  in  many  cases. 

503.  The  kind  of  aestivation,  although  often  the  same  both  in  the 
calyx  and  corolla,  as  in  Parnassia  (Fig.  304)  and  Elodea  (Fig. 
300),  where  both  are  quincuncially  imbricated,  is  as  frequently 
different ;  and  the  difference  is  often  characteristic  of  families  or 
genera.  Thus,  the  calyx  is  valvate  and  the  corolla  convolute  in 
all  Malvacese ;  the  calyx  imbricated  and  the  corolla  convolute  in 
Hypericum,  in  the  proper  Pink  tribe,  &c.  Solitary  exceptions 
now  and  then  occur  in  a  family.  Thus,  the  corolla  in  Rosacese  is 
imbricated,  so  far  as  known,  except  in  Gillenia,  where  it  is  convo- 
lute. In  general  it  may  be  said,  that  the  aestivation  of  the  corolla 
is  more  disposed  to  vary  than  that  of  the  calyx. 

504.  The  Calyx.  In  treating  of  the  general  structure  and  diver- 
sities of  the  flower,  we  have  already  noticed  the  principal  modifi- 
cations of  the  calyx  and  corolla,  as  well  as  the  terms  employed  to 
designate  them  ;  which  need  not  be  here  repeated. 

505.  The  number  of  sepals  that  enter  into  the  composition  of  a 
calyx  is  indicated  by  adjectives  formed  from  the  corresponding 
Greek  numerals  prefixed  to  the  name,  as  disepalous  for  a  calyx  of 
two  sepals;  trisepalous^  of  three  sepals;  tetrasepalous,  of  four; 
pentasepaJous,  of  five ;  hexasepalous,  of  six  sepals  ;  and  so  on. 
Very  commonly,  however,  the  Greek  word  for  leaves,  phylla^  is 
used  in  such  composition ;  and  the  calyx  is  said  to  be  diphyllous, 
triphyllous^  tetr  aphyllous,  pent  aphyllous,  hexaphyllous,  6z;c.,  ac- 
cording as  it  is  composed  of  2,  3,  4,  5,  or  6  leaves  or  sepals  re- 
spectively. These  terms  imply  that  the  leaves  of  the  calyx  are 
distinct,  or  nearly  so.  When  they  are  united  into  a  cup  or  tube, 
the  calyx  was  by  the  earlier  botanists  incorrectly  said  to  be  mono- 
phyllous  (literally  one-leaved) ;  —  a  term  which  we  continue  to  use, 
guarding,  however,  against  the  erroneous  idea  which  its  etymology 
involves,  and  bearing  in  mind  that  the  older  technical  language  in 
botany  expresses  external  appearance,  rather  than  the  real  struc- 
ture, as  we  now  understand  it.  The  correct  term,  calyx  gamophyl' 
lous,  is  now  coming  into  general  use ;  this  literally  expresses  the 
true  state  of  the  case,  and  is  equivalent  to  the  phrase  sepals  united  : 
the  degree  of  coalescence  being  indicated  by  adding  "at  the  base," 
"  to  the  middle,"  or  "  to  the  summit,"  as  the  case  may  be. 


286  THE    FLOWER. 

506.  Still,  in  botanical  descriptions,  it  is  ordinarily  more  con- 
venient and  usual  to  regard  the  calyx  as  a  whole,  and  to  express 
the  degree  of  union  or  separation  by  the  same  terms  as  those 
which  designate  the  degree  of  division  of  the  blade  of  a  leaf  (281- 
283) :  as,  for  example.  Calyx  jive-toothed^  when  the  sepals  of  a 
pentaphyllous  calyx  are  united  almost  to  the  top ;  jive-cleft^  when 
united  to  about  the  middle  ;  jive-parted,  when  they  are  separate 
almost  to  the  base  ;  and  jive-lohed,  for  any  degree  of  division  less 
than  five-parted,  without  reference  to  its  particular  extent.  The 
united  portion  of  a  gamophyllous  calyx  is  called  its  tube  ;  the  dis- 
tinct portions  of  the  sepals  are  termed  the  teeth,  segments,  or  lohes, 
according  to  their  length  as  compared  with  the  tube ;  and  the  ori- 
fice or  summit  of  the  tube  is  named  the  throat.  The  calyx  is  said 
to  be  entire  (281),  when  the  leaves  of  the  calyx  are  so  completely 
confluent  that  the  margin  is  continuous  and  even.  The  terms  reg- 
ular and  irregular  (446,  468)  are  applied  to  the  calyx  or  corolla 
separately,  as  well  as  to  the  whole  flower.  The  counterpart  to 
calyx  monophyllous  or  monosepalous  in  the  current  glossology  is 
polyphyllous  or  polysepalous  (viz.,  of  many  leaves  or  sepals).  This 
is  equivalent  to  the  phrase,  sepals  distinct ;  and  does  not  mean 
that  they  are  unusually  numerous,  or  of  more  than  one  circle. 

507.  The  Corolla  has  corresponding  terms  applied  to  its  modifica- 
tions. When  its  petals  are  distinct  or  unconnected,  it  is  said  to  be 
polypetalous ;  when  united,  at  least  at  the  base,  monopetalous,  or 
more  properly  gamopetalous,  as  already  explained  (461).  The 
united  portions  in  the  latter  case  form  the  tube  of  the  corolla,  and 
the  distinct  parts,  the  lobes,  segments,  &c. ;  and  the  orifice  is  called 
the  throat,  just  as  in  the  calyx.  The  number  of  parts  that  com- 
pose the  corolla  is  designated  in  the  manner  already  mentioned  for 
the  calyx;  —  viz.,  a  corolla  of  two  petals  is  dipetalous;  of  three, 
tripetalous  ;  of  four,  tetrapetalous  ;  of  five,  pentapetalov^ ;  of  six, 
hexapetalous  ;  of  seven,  heptapetalous ;  of  eight,  octopetalous  ;  of 
nine,  enneapetalous  ;  often,  decapetalous. 

508.  Frequently  the  petals,  and  rarely  the  sepals,  taper  into  a 
stalk  or  narrow  base,  analogous  to  the  petiole  of  a  leaf,  which  is 
called  the  claw  (unguis) ;  and  hence  the  petal  is  said  to  be  unguic- 
ulate  (as  in  Cruciferous  flowers,  the  Pink,  Fig.  302,  and  Gynan- 
dropsis.  Fig.  352,  &c.)  ;  the  expanded  portion,  like  that  of  the 
leaf,  being  distinguished  by  the  name  of  the  lamina,  limb,  or  blade. 

509.  Some   kinds   of  polypetalous   flowers  receive   particular 


THE    COROLLA. 


287 


names,  from  the  form  or  arrangement  of  their  floral  envelopes, 
especially  of  the  corolla.  Among  the  regular  forms  (295)  we 
may  mention  the  rosaceous  flower,  like  that  of  the  Rose,  Apple, 
&c.,  where  the  spreading  petals  have  no  claws,  or  very  short 
ones  ;  the  liliaceous^  of  which  the  Lily  is  the  type,  where  the  claws 
or  base  of  the  petals  or  sepals  are  erect,  and  gradually  spread  to- 
wards their  summits ;  the  caryophyllaceous,  as  in  the  Pink  and 
Silene,  where  the  five  petals  have  long  and  narrow  claws,  which 
are  inclosed  in  the  tube  of  the  calyx ;  and  the  cruciate,  or  cruci- 
form, which  gives  name  to  the  Mustard  Family  (see  Ord.  Cru- 
ciferse),  where  the  four  unguiculate  petals,  diverging  equally  from 
one  another,  are  necessarily  disposed  in  the  form  of  a  cross,  as  in 
the  Mustard,  &c.  Among  the  irregular  polypetalous  flowers, 
which  are  greatly  varied  in  different  families,  the  papilionaceous 
or  hutterjly-shaped  corolla  of  the  Pea  tribe  has  already  been  de- 
scribed (468). 

510.  Several  forms  of  the  gamopetalous  corolla,  or  gamophyl- 
lous  calyx,  have  been  distinguished  by  particular  names.  These 
are  likewise  divided  into  the  regular,  where  their  parts  are  equal 
in  size,  or  equally  united ;  and  the  irregular,  where  their  size  or 
degree  of  union  is  unequal  (468).  Among  the  former  are  the 
campanulate,  or  hell-shaped,  as  the  corolla  of  the  Harebell  (Fig. 
364),  which  enlarges  gradually  and  regularly  from  the  base  to  the 


summit ;  the  infundibuliform,  or  funnel-shaped,  where  the  tube 
enlarges  very  gradually  below,  but  expands  widely  at  the  summit, 
as  in  the  corolla  of  Morning  Glory  (Ord.  Convolvulacese)  and  the 

FIG.  364.  Campanulate  corolla  of  Campanula  rotundifolia.  365.  Salver-shaped  corolla  of 
Phlox.  366.  Labiate  (ringenl)  corolla  of  Lamium ;  a  side  view,  367.  Personate  corolla  of 
Antirrhinum.    368.  Personate  corolla  of  Linaria,  spurred  at  the  base. 


288  THE    FLOWER. 

Tobacco  (Ord.  Solanaceae)  ;  tubular^  where  the  form  is  cylindrical 
throughout;  hyyocrateriform^  or  salver-shaped^  where  the  limb 
spreads  at  right  angles  with  the  summit  of  the  more  or  less  elon- 
gated tube,  as  in  the  corolla  of  Primula  and  of  Phlox  (Fig.  365)  ; 
and  rotate^  or  wheel-shaped^  when  a  hypocrateriform  corolla  has  a 
very  short  tube,  as  in  the  Forget-me-not  (Ord.  Boraginacece)  and 
Bittersweet  (Ord.  Solanacese). 

511.  The  principal  irregular  gamopetalous  or  gamophyllous 
form  that  has  received  a  separate  appellation  is  the  labiate  or  bi- 
labiate, which  is  produced  by  the  unequal  union  of  the  sepals  or 
petals  (470),  so  as  to  form  an  upper  and  a  lower  part,  or  two  lips, 
as  they  are  called,  from  an  obvious  resemblance  to  the  open  mouth 
of  an  animal  (Fig.  366).  This  variety  is  almost  universally  ex- 
hibited by  the  corolla  of  Labiatae,  and  very  frequently  by  the  calyx 
also,  as  in  the  Sage  (Ord.  Labiatse)  :  it  likewise  occurs  in  the  co- 
rolla of  most  Honeysuckles  (Ord.  Caprifoliacese),  and  in  the  calyx 
of  many  papilionaceous  flowers.  When  the  upper  lip  is  arched, 
as  in  the  corolla  of  Lamium  (Fig.  366),  it  is  sometimes  called  the 
galea,  or  helmet.  When  the  two  lips  are  thus  gaping  and  the 
throat  open,  the  corolla  is  said  to  be  ringent.  But  when  the  mouth 
is  closed  by  the  approximation  of  the  two  lips,  and  especially  by 
an  elevated  portion  or  protuberance  of  the  lower,  called  the  palate, 
as  in  the  Snapdragon  (Fig.  367)  and  Toad-flax  (Fig.  368),  the 
corolla  is  said  to  be  personate,  or  masked. 

512.  In  the  Snapdragon,  the  base  of  the  corolla  is  somewhat 
protuberant,  or  saccate,  on  the  anterior  side  (Fig.  367)  :  in  the 
Toadflax  (Fig.  368)  the  protuberance  is  extended  into  a  hollow 
spur.  A  projection  of  this  kind  is  not  uncommon,  in  various 
families  of  plants.  One  petal  of  the  Violet  is  thus  spurred  or 
calcaraie ;  so  is  one  of  the  outer  petals  in  the  Fumitory,  and  each 
of  them  in  Dicentra  (Fig.  295).  So,  also,  one  of  the  sepals  is 
spurred  or  strongly  sac-shaped  in  the  Jewel- weed  (Impatiens),  the 
Nasturtium,  and  the  Larkspur  ;  and  all  five  petals  take  this  shape 
in  the  Columbine.  A  monster  of  the  Toadflax  is  occasionally 
found,  in  which  the  four  remaining  petals,  of  the  five  which  enter 
into  its  composition,  affect  the  same  irregularity,  and  so  bring  back 
the  flower  to  a  singular  abnormal  state  of  regularity.  This  was 
called  by  Linnseus  Peloria ;  a  name  which  is  now  used  to  desig- 
nate the  same  sort  of  monstrosity  in  different  flowers. 

513.  The  petals  are  sometimes  furnished  with  appendages  on 


THE    STAMENS.  289 

their  inner  surface,  such  as  the  crown  at  the  summit  of  the  claw  in 
Silene  (Fig.  302),  and  the  scales  similarly  situated  on  the  gamo- 
petalous  corolla  of  Myosotis  and  Symphytum  (Ord.  Boraginacese). 
The  nature  of  this  crown  has  already  been  explained  (458).  Such 
appendages  are  sometimes  thought  to  represent  an  adherent  row 
of  abortive  stamens  or  petals. 

514.  The  bodies  termed  nectaries  (485)  by  the  old  botanists  are 
either  petals  of  unusual  form,  such  as  the  spurs  of  the  Columbine  ; 
or  petals  passing  into  stamens,  such  as  the  fringe  of  the  Passion- 
flower ;  or  a  deduplication  of  the  petal,  as  in  Parnassia  (Fig.  305)  ; 
or  else  abortive  and  transformed  stamens,  as  in  Canna.  The 
so-called  nectary  of  Orchidaceous  plants  is  merely  a  petal,  which, 
being  of  a  different  shape  from  the  others,  is  termed  the  laheUum. 

515.  The  duration  of  the  floral  envelopes  varies  greatly  in  dif- 
ferent plants.  Sometimes  they  fall  ofl*  as  the  flower  opens,  or  even 
before  expansion,  as  the  calyx  of  the  Poppy  and  the  corolla  of  the 
Grape-vine  (Fig.  334) ;  when  they  are  said  to  be  caducous.  More 
commonly  they  are  deciduous,  or  fall  after  anlhesis  but  before  the 
fruit  forms.  When  they  remain  until  the  fruit  is  formed  or  ma- 
tured, they  are  persistent.,  which  is  often  the  case  with  the  calyx, 
especially  when  it  has  a  green  color  and  foliaceous  texture.  It  is 
occasionally  accrescent,  or  takes  a  farther  growth  during  fructifica- 
tion, as  in  Physalis.  When  the  envelopes  persist  in  a  dry  or  with- 
ering state,  as  the  corolla  of  Heaths,  of  Campanula,  &c.,  they  are 
said  to  be  marcescent. 

516.  Besides  serving  as  organs  of  protection,  the  sepals,  when 
green,  assimilate  sap,  and  act  upon  the  air  like  ordinary  foliage 
(344,  346).  The  petals,  like  other  uncolored  (that  is  greenless) 
parts,  do  not  evolve  oxygen,  but  abstract  it  from  the  air,  and  give 
off*  carbonic  acid  ;  in  other  words,  they  decompose  assimilated  mat- 
ter,—  a  process  which  appears  to  be  needful  in  flowering,  and  to 
subserve  some  important  end  at  the  time  (367-373).  The  tissue 
of  a  petal  is  much  the  same  as  that  of  a  leaf,  except  that  it  is  much 
more  delicate,  and  the  fibro-vascular  system  is  reduced  to  slender 
bundles  of  a  few  spiral  vessels,  &c.,  which  form  its  veins. 

Sect.  VI.     The  Stamens. 

517.  The  Stamens,  collectively  forming  the  Andrcecium  (418), 
have  been  already  considered  in  respect  to  their  component  parts, 

25 


290  THE    FLOWER. 

their  nature  and  symmetry,  and  their  principal  modifications  as  to 
relative  number  and  disposition.  Their  absolute  number  in  the 
flower,  it  may  be  remarked,  is  designated  by  Greek  numerals  pre- 
fixed to  the  word  used  for  stamens,  as  employed  by  Linnaeus  in  the 
names  of  his  artificial  classes.  Thus,  a  flower  whh  one  stamen  is 
said  to  be  monandrous ;  with  two,  diandrous ;  with  three,  trian- 
drous ;  with  four,  telrandrous ;  with  five,  pentandrous ;  with  siv, 
hexandrous ;  with  seven,  heptandrous  ;  with  eight,  octandrous  ; 
with  nine,  enncandrous ;  with  ten,  decandrous ;  with  twelve, 
dodecandrous ;  and  with  a  greater  or  indefinite  number,  polyan- 
drous.  (See  the  account  of  the  classes  of  the  LinnaBan  Artificial 
System,  in  Part  II.) 

518.  The  terms  employed  to  designate  their  various  modifica- 
tions, most  of  which  have  already  been  incidentally  noticed,  are 
likewise  derived  from  the  names  of  Linnsean  artificial  classes,  with 
the  exception  of  those  which  relate  to  their  insertion ;  namely,  as 
hypogynous^  when  inserted  on  the  receptacle  (466),  or,  in  other 
words,  free  from  all  adhesion  to  neighbouring  organs  ;  perigynous, 
when  adherent  to  the  tube  of  the  calyx  (as  in  Fig.  315) ;  and  epi- 
gynouSj  when  adherent  also  to  the  ovary,  and,  as  it  were,  raised 
to  its  summit  (as  in  Fig.  316).  To  these  may  be  added  the  Lin- 
nsean term  gynandrous,  expressive  of  their  further  cohesion  with 
the  style,  as  in  the  Orchis  Family  (Ord.  Orchidacese). 

519.  As  to  mutual  cohesion,  they  are  monadelphous  when  united 
by  their  filaments  into  one  body  (as  in  Fig.  307) ;  diadelphous, 
when  thus  combined  in  two  sets  (as  in  Fig.  308) ;  triadelphous^ 
when  in  three  sets,  as  in  Hypericum  and  Elodea  (Fig.  300,  301) ; 
pentadelphous,  when  in  five  sets,  as  in  our  Linden ;  and  polyadel- 
phous, when  in  several  sets,  irrespective  of  the  particular  number. 
They  are  syngenesious,  when  united  by  their  anthers  (Fig.  309, 
310).  As  respects  inequality  of  size,  they  are  didynamous,  when 
four  stamens  constitute  two  pairs  of  unequal  length  (481)  ;  and 
tetradynamous,  when  six  stamens  only  are  present,  two  of  which 
are  shorter  than  the  others,  as  in  Cruciferous  flowers  (455)  ;  a 
case  which  is  sometimes,  but  less  distinctly,  seen  in  the  allied  Caper 
Family  (Fig.  352).  Their  complete  suppression  in  some  flowers 
gives  rise  to  such  terms  as  moncRcious,  dicpxious,  and  polygamous, 
which  have  already  been  defined  (473). 

520.  The  proportion  of  the  stamens  to  the  corolla  or  other  floral 
envelopes  is  sometimes  to  be  noticed.     When  they  are  longer  and 


THE    STAMENS.  291 

protruding,  they  are  said  to  be  exserted ;  when  shorter  or  concealed 
within,  they  are  included  ;  —  terms  which  apply  to  other  organs  as 
well.  So  of  terms  which  indicate  their  direction  ;  as  declined,  when 
curved  towards  one  side  of  the  blossom,  as  in  the  Horsechestnut. 

521.  The  stamens  are  mostly  too  narrow  to  furnish  any  charac- 
ters of  aestivation,  except  as  to  the  manner  in  which  each  one  is 
separately  disposed.  In  this  respect  they  exhibit  several  varieties, 
to  which  the  same  terms  are  applied  as  to  the  vernation  of  indi- 
vidual leaves  (257). 

522.  When  the  stamen  is  destitute  of  the  filament,  or  stalk  (Fig. 
369,  a),  the  anther  (b)  is  said  to  be  sessile :  the 

filament  being  no  more  essential  to  the  stamen     j    — -C\ 

than  the  claw  is  to  the  petal,  or  the  petiole  to  :^>^ 

the  leaf.     When  the  anther  is  imperfect,  abor-     ^    Vi 

tive,  or  wanting,  the  stamen  is  said  to  be  sterile,  \\ 

abortive,  or  rudimentary ;  its  real  nature  being  \\ 

known  by  its  situation.  \\ 

523.  The   Filament,  although   usually  slender  seg 
and  cylindrical,  or  slightly  flattened,  assumes  a 

great  variety  of  forms :  it  is  sometimes  dilated  so  as  to  be  undis- 
tinguishable  from  the  petals,  except  by  its  bearing  an  anther ;  as 
in  the  transition  states  between  the  true  petals  and  stamens  of 
Nymphsea  (White  Water-Lily,  Fig.  266,  267).  The  filament  is 
anatomically  composed  of  a  central  bundle  of  spiral  vessels  or 
ducts,  which  represents  the  fibro-vascular  system  of  the  leaf,  in 
the  same  state  as  in  the  petiole,  enveloped  by  parenchyma ;  the 
outer  stratum  of  which  forms  a  delicate  epidermis. 

524.  The  Anther  (Fig.  369,  b),  which  is  the  essential  part  of  the 
stamen,  is  usually  borne  on  the  apex  of  the  filament;  and  com- 
monly consists  of  two  lobes,  or  cells  (theccc),  placed  side  by  side, 
and  connected  by  a  prolongation  of  the  filament  called  the  connec- 
tivum,  or  connective.  As  the  filament  answers  to  the  petiole,  so 
the  connectivum  answers  to  the  midrib  of  the  leaf,  and  the  lobes, 
or  cells,  to  the  blade  of  the  leaf ;  the  portion  each  side  of  the  mid- 
rib forming  an  anther-lobe.  The  pollen,  or  powdery  substance 
contained  in  the  anther,  originates  from  a  peculiar  transformation 
of  the  cellular  tissue,  or  parenchyma  of  the  leaf. 

525.  The  attachment  of  the  anther  to  the  filament  presents  three 
principal  modes.  1st.  When  the  base  of  the  connective  exactly 
corresponds  with  the  apex  of  the  filament  and  with  the  axis  of  the 


292 


THE    FLOWER. 


anther,  the  latter  is  termed  innate^  and  rests  firmly  upon  the  summit 

of  the  filament,  as  in  Fig.  370.  2d. 
When  the  lobes  of  the  anther  adhere 
for  their  whole  length  to  a  prolonga- 
tion of  the  filament,  or  to  a  broad  con- 
nective (whichever  it  be  called),  so  as 
to  appear  lateral,  it  is  said  to  be  ad- 
nate;  as  in  the  Magnolia  (Ord.  Mag- 
noliacese).  Here  the  anther  must  be 
either  extrorse  or  introrse.  It  is  in- 
trorse,  or  turned  inwards,  when  it  oc- 
cupies the  inner  side  of  the  connec- 
tive, and  faces  the  pistils,  as  in  Mag- 
nolia and  the  Water-Lily  (Fig.  266) ;  but  when  the  anther  looks 
away  from  the  pistils  and  towards  the  petals  or  sepals,  it  is  said  to 
be  extrorse,  or  turned  outwards,  as  in  the  Iris,  in  Liriodendron 
(Fig.  371),  and  in  Asarum  (Fig.  373).  3d.  When  the  anther  is 
fixed  by  a  point  to  the  apex  of  the  filament,  on  which  it  lightly 
swings,  it  is  said  to  be  versatile ;  as  in  all  Grasses,  in  the  Lily,  and 
in  the  Evening  Primrose  (Fig.  372),  &c.  In  this  case,  as  in  the 
preceding,  the  anther  is  said  to  be  introrse,  or  incumbent,  when  it 
is  turned  towards  the  pistil,  which  is  the  most  common  form  ;  and 
extrorse,  when  it  faces  outwards. 

526.  The  connective  is  frequently  inconspicuous  or  almost  want- 
ing, so  that  the  lobes  of  the  anther  are  directly  in  contact 

on  the  apex  of  the  filament;  as  in  Euphorbia  (Fig.  346). 
It  is  often  produced  beyond  them  into  an  appendage,  as  in 
the  Magnolia  and  Liriodendron  (Fig.  371),  the  Papaw  (Ord. 
Anonaceae,  where  it  forms  a  rounded  top),  and  Asarum 
(Fig.  373).  Appendages  or  processes  from  the  back  of  the 
connective  are  seen  in  the  stamens  of  the  Violet,  and  of 
many  Ericaceous  plants  (see  Ord.  Ericaeese). 

527.  Each  of  the  two  cells  or  lobes  of  the  anther  is  marked 
with  a  lateral  line  or  furrow,  running  from  top  to  bottom ;  this  is 
the  suture,  or  line  of  dehiscence,  by  which  the  anther  opens  at 
maturity,  and  allows  the  pollen  to  fall  out  (Fig.  369).     This  line, 


FIG.  370.  Stamen  of  Isopyrum  biternatum,  with  an  innate  anther.  371.  Stamen  of  Lirio- 
dendron, or  Tulip-tree,  with  an  adnate  extrorse  anther.  372.  Stamen  of  (Enothera  glauca,  with 
the  anther  fixed  by  its  middle  and  versatile. 

FIG.  373.    Stamen  of  Asarum  Canadense,  with  an  adnate  anther. 


THE    ANTHER.  293 

which  answers  to  the  margin  of  the  leaf,  is  exactly  lateral  in  in- 
nate anthers,  as  in  Fig.  370 ;  but  it  looks  more  or  less  evidently, 
and  often  directly,  inward  in  introrse,  and  outward  in  extrorse  an- 
thers (Fig.  371,  373). 

528.  Various  deviations  from  this  normal  structure  of  the  anther 
frequently  occur  ;  some  of  which  may  be  cursorily  noticed.  The 
opening  of  the  anther,  sometimes  called  its  dehiscence,  does  not 
always  take  place  by  a  longitudinal  fissure  for  the  whole  length  of 
the  cell.  Occasionally  the  suture  opens  only  at  the  top,  in  the 
form  of  a  chink  or  pore ;  as  in  Pyrola,  Rhododendron,  &c.  (Ord. 
Ericacese),  and  in  the  Potato,  &c.  Sometimes  the  summit  of  the 
lobes  is  prolonged  into  a  tube,  which  opens  by  a  pore  or  chink  at 
the  apex  ;  as  in  the  Heath  and  Huckleberry  (Ord.  Ericacess).  In 
the  Barberry  (Ord.  Berberidacese )  and  other  plants  of  the  family, 
the  Benzoin,  &c.,  nearly  the  whole  face  of  each  anther-cell  sepa- 
rates by  a  continuous  line,  forming  a  kind  of  door,  which  is  attached 
at  the  top,  and  turns  back,  as  if  on  a  hinge  :  in  this  case  the  anthers 
are  said  to  open  by  valves.  In  the  Sassafras  (Ord.  Lauracese), 
and  other  plants  of  the  Laurel  Family,  each  lobe  of  the  anther 
opens  by  two  such  valves,  like  trap-doors. 

529.  Sometimes  the  anthers  are  one-celled  by  the  suppression 
of  one  lobe,  being  dimidiate,  or  reduced  as  it  were  to  half-stamens, 
as  m  Gomphrena,  and  some  other  Amaranthaceous  plants  ;  but 
they  more  frequently  become  one-celled  by  the  confluence  of  the 
two  lobes,  and  the  disappearance  of  the  partition  between  them. 
The  kidney-shaped  one-celled  anthers  of  the  Mallow  Family  may 
be  conceived  to  arise  from  the  divergence  of  the  base  of  the  two 
lobes,  and  their  perfect  confluence  at  the  apex ;  and  the  opening 
consequently  takes  place  by  a  continuous  sutural  line  passing  round 
the  margin  (Ord.  Malvaceae).  A  somewhat  similar  case  occurs  in 
Monarda  and  some  other  plants  of  the  Mint  Family,  where  only 
one  of  the  two  lobes  remains  parallel  with  the  filament  or  con- 
nective ;  while  the  other,  describing  a  semicircle,  is  brought  into 
the  same  vertical  line,  where  it  stands  bottom  upwards ;  and  the 
two,  cohering  by  their  contiguous  extremities,  become  confluent 
into  a  single  cell,  which  opens  by  a  continuous  straight  line  from 
one  end  to  the  other.  The  anther  of  Teucrium  differs  from  the 
last  chiefly  in  the  enlarged  connective,  on  which  the  divaricate 
lobes  rest ;  and  the  cells,  at  first  distinct,  are  confluent  into  one 
after  the  anther  opens.     In  the  Thyme,  the  anther-lobes  are  also 

25* 


294  THE    FLOWER. 

greatly  divergent,  but  are  separated  by  the  thickened  connective, 
which  in  this  family  is  often  larger  than  the  cells.  In  the  Sage, 
the  singular  elongated  connective  sits  astride  the  apex  of  the  fil- 
ament, and  bears  an  anther-cell  at  each  extremity ;  one  of  which 
is  perfect  and  contains  pollen,  while  the  other  is  imperfect  or  abor- 
tive. Illustrations  of  these  diversities  will  be  found  under  the  Ord. 
Labiatse.  We  have  no  room  to  pass  in  review  even  the  more 
common  of  the  almost  endless  variations  which  the  anther  exhibits. 

530.  As  to  its  structure,  each  lobe  of  the  full-grown  anther  con- 
sists of  an  epidermal  membrane,  lined  with  a  delicate  fibrous  tis- 
sue, and  surrounding  a  cavity  filled  with  pollen.  This  fibrous 
lining,  a  part  of  which  is  shown  in  Fig.  32,  from  the  anther  of 
Cobsea,  is  composed  of  simple  or  branching  attenuated  threads  or 
bands,  which  formed  the  thickening  deposit  on  the  walls  of  large 
parenchymatous  cells ;  all  the  membrane  between  the  bands  be- 
coming obliterated  as  the  anther  approaches  maturity,  the  latter 
alone  remain,  as  a  set  of  delicate  fibres.  This  fibrous  layer  grad- 
ually diminishes  in  thickness  as  it  approaches  the  line  of  dehis- 
cence of  the  cell,  and  there  it  is  completely  interrupted.-  These 
very  elastic  and  hygrometric  threads  lengthen  or  contract  in  differ- 
ent ways,  according  as  the  anther  is  dry  or  moist ;  which  move- 
ments, after  the  pollen  has  appropriated  all  the  juices  of  the  tissue, 
aid  in  the  disruption  of  the  anther  along  the  suture,  and  then  favor 
the  egress  of  the  pollen.  The  walls  of  many  anthers  are  curved 
outwards,  or  completely  turned  inside  out,  as  in  Grasses,  by  the 
unlike  hygrometric  state  of  the  external  and  the  internal  layers. 

531.  Of  all  the  floral  organs,  the  anther  shows  least  likeness  to 
a  leaf.  Nevertheless,  the  early  development  is  nearly  the  same. 
Like  the  leaf,  the  apex  is  earliest  formed,  appearing  first  as  a  solid 
protuberance,  and  the  anther  is  completed  before  the  filament, 
which  answers  to  the  leaf-stalk,  makes  its  appearance.  At  first, 
the  anther  is  of  a  greenish  hue,  although  at  maturity  the  cells 
assume  a  different  color,  more  commonly  yellow.  A  transverse 
section  of  the  forming  anther  shows  four  places  in  which  the  trans- 
formation of  the  parenchyma  into  pollen  commences,  which  an- 
swer to  the  centre  of  the  four  divisions  of  the  parenchyma  of  a 
leaf,  viz.  the  two  sides  of  the  blade,  each  distinguished  into  its 
upper  and  its  lower  stratum.  So  that  the  anther  is  primarily  and 
typically  four-celled  ;  each  lobe  being  divided  by  a  portion  of  un- 
transformed  tissue  stretching  from  the  connective  to  the  opposite 


THE    POLLEN.  295 

side,  which  corresponds  to  the  margin  of  the  leaf  and  the  line  of 
dehiscence.  This  appearance  is  presented  by  a  large  number  of 
full-grown  anthers  :  but  the  partition  usually  disappears  before  the 
anther  opens,  when  each  lobe  becomes  single-celled.  The  normal 
anther  is  consequently  considered  as  two-celled.  In  Menispermum 
and  Cocculus  (Ord.  Menispermacese)',  however,  the  anther  is 
strongly  four-lobed  externally,  and  each  lobe  forms  a  distinct  cell, 
at  maturity.  Although  the  stamens  originate  a  little  later  than  the 
petals,  when  these  are  present,  yet  they  outgrow  them  at  first,  and 
their  formation  is  earlier  completed  (489). 

532.  The  Pollen,  contained  in  the  anther,  which  appears  to  the 
naked  eye  like  a  mere  powder,  consists  of  grains  of  definite  size 
and  shape,  which  are  uniform  in  the  same  plant,  but  often  very 
different  in  different  species  or  natural  families.  Although  com- 
monly spherical  or  oval,  they  are  cylindrical  in  the  Spiderwort 
(Tradescantia),  nearly  square  in  Colutea,  many-sided  in  the  Tea- 
sel, and  triangular,  with  the  angles  dilated  and  rounded,  in  the 
Evening  Primrose  (Fig.  419).  The  most  remarkable  shape  is 
that  of  Zostera  (a  marine  aquatic  plant),  in  which  the  grains  con- 
sist of  long  and  slender  threads,  which,  as  they  lie  side  by  side  in 
the  anther,  resemble  a  skein  of  silk.  Their  surface,  although  more 
frequently  smooth  and  even,  is  banded  or  crested  in  many  cases ; 
it  is  reticulated  in  the  Passion-flower,  and  studded  with  strong 
points  in  Convolvulus  purpureus  (Fig.  417),  or  short  bristles  in  the 
Mallow  Family  and  the  Gourd.     The  color  is  usually  yellow. 

533.  The  grains  of  pollen  are  single  cells,  formed  usually  in 
fours,  by  the  division  of  the  living  contents  of  mother  cells  first 
into  two,  and  these  again  into  two  parts,  which,  acquiring  a  layer 
of  cellulose,  become  four  specialized  cells,  nearly  in  the  manner 
already  described  (31,  95).  As  the  pollen  completes  its  growth, 
the  walls  of  the  mother  cells  are  usually  absorbed  or  obliterated, 
when  the  grains  lie  loose  in  the  cell.  But  sometimes  the  inclosing 
cells  persist,  and  collect  the  pollen-grains  into  coherent  masses  of 
various  consistence,  as  in  the  Milkweed  Family  (Fig.  422)  and  in 
the  Orchis  Family  (Ord.  Orchidacese).  Such  pollen-masses  are 
sometimes  called  polUnia.  The  threads,  like  cobweb,  that  are 
loosely  mixed  with  the  pollen  of  the  Evening  Primrose  (Ord.  Ona- 
gracese),  are  vestiges  of  nearly  obliterated  mother  cells. 

534.  Not  unfrequently  the  four  grains  developed  in  the  same 
cell  cohere,  more  or  less  firmly,  as  in  most  Ericaceous  plants ;  or 


296  THE    FLOWER. 

grow  as  one  compound  grain,  without  undergoing  complete  di- 
vision. The  grains  of  the  pollen  of  the  Evening  Primrose  Fam- 
ily (Fig.  419)  thus  consist  of  the  rudiments  of  four,  which  remain 
in  strict  combination ;  one  of  them  enlarging  to  form  the  main 
body  of  the  grain,  while  the  three  others  appear  as  bosses  on  its 
angles.  Rarely  the  four  cohering  grains  are  placed  in  the  same 
plane.  They  usually  stand  in  the  same  relation  to  each  other  as 
the  four  angles  of  a  cube.  In  the  Mimosa  Family,  the  division 
goes  farther,  and  gives  rise  to  eight  or  sixteen  lightly  coherent 
grains  in  each  mass. 

535.  The  pollen-grains  have  two  coats ;  the  exterior  of  which, 
called  the  extine^  is  quite  firm  and  often  wax-like,  granular,  or 
fleshy ;  to  it  the  bands,  points,  or  other  markings  belong.  It  is 
thought  by  Schleiden  and  others  to  be  a  secretion  from  the  inner 
layer,  which,  on  this  view,  is  considered  as  the  proper  membrane 
of  the  cell.  This  inner  coat,  named  the  inline^  is  very  thin,  trans- 
parent, and  highly  extensible.  It  absorbs  water  rapidly,  and  when 
exposed  to  its  action  the  grain  swells  and  soon  bursts,  discharging 
its  contents.  These  contents  are  a  fluid,  which  appears  slightly 
turbid  under  the  higher  powers  of  ordinary  microscopes,  but,  when 
submitted  to  a  magnifying  power  of  three  hundred  diameters,  it  is 
found  to  contain  a  multitude  of  minute  particles  (foviUcB)  of  spher- 
ical or  oblong  form,  the  larger  of  which  are  from  the  four-thou- 
sandth to  the  five-thousandth  of  an  inch  in  length,  and  the  smaller 
only  one  fourth  or  one  sixth  of  this  size.  The  smaller  exhibit  the 
constant  molecular  motion  of  all  such  minute  particles  when  sus- 
pended in  a  liquid  and  viewed  under  a  sufficient  magnifying  power. 
The  larger  are  now  thought  by  some  to  be  substantially  of  the  na- 
ture of  starch-grains.  A  third,  intermediate  membrane  has  been 
detected  in  certain  cases.  The  pollen  of  some  plants  —  that  of  Zos- 
tera  very  distinctly  —  has  only  a  single  (the  internal)  membrane. 

536.  When  wetted,  the  grains  of  pollen  promptly  absorb  water 
by  endosmosis  (37),  and  are  distended,  changing  their  shape  some- 
what, and  obliterating  the  longitudinal  folds,  one  or  more  in  num- 
ber, which  many  grains  exhibit  in  the  dry  state.  Soon  the  more 
extensible  and  elastic  inner  coat  inclines  to  force  its  way  through 
the  weaker  parts  of  the  exterior,  especially  at  one  or  more  thin 
points  or  pores.  The  absorption  continuing,  the  distention  soon 
overcomes  the  resistance  of  the  inner  coat,  which  bursts,  with  the 
eruption  of  the  contents  in  a  jet.     When  the  pollen  falls  upon  the 


THE    PISTILS.  297 

Stigma,  however,  which  is  barely  moist,  but  not  wet,  it  does  not 
burst,  but  the  inner  membrane  is  slowly  protruded,  often  through 
particular  points,  clefts,  or  valvular  openings  of  the  outer  coat,  in 
the  form  of  an  attenuated  transparent  tube  (Fig.  416-418),  filled 
with  its  fluid  contents,  which  penetrates  the  naked  and  loose  cellu- 
lar tissue  of  the  stigma,  and  buries  itself  in  the  style  (Fig.  419). 
Its  further  course  and  the  office  it  subserves  will  be  considered 
after  the  structure  of  the  pistil  is  made  known. 

Sect.  VII.     The  Pistils. 

537.  The  Pistils  (419)  occupy  the  centre  of  the  flower,  and  ter- 
minate the  axis  of  growth.  Their  number  is  designated  by  Greek 
numerals,  prefixed  to  the  name  applied  to  the  pistil  from  the  same 
language.  Thus,  a  flower  with  a  single  pistil  is  said  to  be  mono- 
gynous ;  with  two,  digynous ;  with  three,  irigynous ;  with  four, 
tetragynous  ;  with  five,  pentagynous  ;  with  six,  hexagynous  ;  with 
seven,  heplagynous ;  with  eight,  octogynous ;  with  ten,  decagynous ; 
and  so  on  :  and  when  more  numerous  or  indefinite,  they  are  termed 
poly gy nous.     (See  the  Linnsean  Artificial  Orders.) 

538.  It  is  comparatively  seldom  that  the  pistils  are  actually 
equal  to  the  petals  or  sepals  (480)  in  number;  they  are  some- 
times more  numerous,  and  arranged  in  several  rows  upon  the 
enlarged  or  prolonged  receptacle,  as  in  the  Magnolia,  the  Straw- 
berry, &c.,  and  perhaps  more  frequently  they  are  reduced  to  less 
than  the  typical  number,  or  to  a^single  one.  Yet  often  what  ap- 
pears to  be  a  single  pistil  is  not  so  in  reality,  but  a  compound  or- 
gan, formed  by  the  ynion  of  two,  three,  or  a  greater  number  of 
simple  pistils;  as  is  shown  in  Fig.  381-390. 

539.  A  pistil,  as  already  described  (420),  is  composed  of  three 
parts ;  the  Ovary,  or  seed-bearing  portion  ;  the  Style,  or  taper- 
ing portion,  into  which  the  apex  of  the  ovary  is  prolonged ;  and 
the  Stigma,  usually  situated  at  the  summit  of  the  style,  consisting 
of  a  part,  or  sometimes  a  mere  point,  of  the  latter,  divested  of  epi- 
dermis, with  its  moist  cellular  tissue  exposed  to  the  air.  The 
ovary,  which  contains  the  young  seeds,  or  ovules,  is  of  course  a 
necessary  part  of  the  pistil :  the  stigma,  which  receives  from  the 
anthers  the  pollen  (536)  by  which  the  ovules  are  fertilized,  is  no 
less  necessary :  but  the  intervening  style  is  no  more  essential  to 
the  pistil  than  the  filament  is  to  the  stamen,  and  is  therefore  not 


298 


THE    FLOWER. 


uncommonly  wanting.  In  the  latter  case,  the  stigma  is  sessile 
upon  the  apex  of  the  ovary.  In  Tasmannia  it  actually  occupies 
the  side  of  the  ovary  for  nearly  its  whole  length,  and  is  separated 
from  the  line  to  which  the  ovules  are  attached  only  by  the  thick- 
ness of  the  walls ;  and  it  is  nearly  the  same  in  our  Schizandra 
(Fig.  375),  another  plant  of  the  Magnolia  Family.  The  style 
sometimes  proceeds  from  the  side,  or  even  from  the  apparent 
base,  of  the  ovary  ;  as  in  the  Strawberry. 

540.  When  the  pistil  is  reduced  to  a  single  one,  or  when  several 
coalesce  into  one,  it  will  necessarily  terminate  the  axis,  and  appear 
to  be  a  direct  continuation  of  it.  When  there  are  two  pistils  in 
the  flower,  they  always  stand  opposite  each  other  (so  that  if  they 
coalesce  it  is  by  their  inner  faces) ;  and  are  either  lateral  as  re- 
spects the  flower,  that  is,  one  on  the  right  side  and  the  other  on  the 
left,  in  a  plane  at  right  angles  to  the  bract  and  axis  (444),  as  in  the 
Mustard  Family,  the  Gentian  Family,  and  a  few  others  ;  or,  more 
commonly,  anteridr  and  posterior^  one  before  the  axis  and  the 
other  before  the  bract  of  the  axillary  flower.  When  they  accord 
in  number  with  the  sepals  or  petals,  they  are  either  opposed  to  or 
alternate  with  them ;  and  the  two  positions  in  this  respect  are 
sometimes  found  in  nearly  related  genera,  so  as  to  baffle  our  at- 
tempts at  explaining  the  cause  of  the  difference.  In  Pavonia,  for 
example,  the  five  pistils  are  opposite  the  petals ;  in  Malvaviscus 
and  Hibiscus,  alternate  with  them.  In  Sida,  when  five,  they  stand 
opposite  the  petals ;   in  Abutilon,  opposite  the  sepals. 

541.  To  attain  a  correct  morphological  view  of  the  simple  pistil, 
we  must  contemplate  it  as  resulting  from  the  transformation  of  a 
leaf  which  is  folded  inwards,  and  the  margins  united  ;  in  a  manner 
that  will  be  perfectly  evident  on  comparing  Fig.  263  with  Fig. 
270.  The  line  formed  by  the  union  of  the  margins  of  the  leaf  is 
called  the  Inner  or  Ventral  Suture,  and  always  looks  towards 
the  axis  of  the  flower.  This  is  a  true  suture,  or  seam^  as  the  word 
denotes.  The  opposite  line,  which  answers  to  the  midrib,  is  some- 
times apparent  as  a  thickened  line,  and  is  termed  the  Outer  or 
Dorsal  Suture.  The  surface  of  the  pistil  necessarily  corresponds 
to  the  lower,  and  its  lining  to  the  upper,  surface  of  a  leaf.  The 
stalk  of  the  pistil  (487),  when  it  is  present,  represents  the  petiole ; 
and  a  prolongation  of  the  apex  of  the  specialized  leaf  forms  the 
style.  The  stigma  occupies  some  portion  of  what  in  the  style  an- 
swers to  the  confluent  margins  of  the  transformed  leaf  (and  cer- 


THE    PISTILS. 


299 


tainly  is  not  a  portion  of  the  midrib,  as  has  been  thought) ;  this  is 
evident  in  Tasmannia,  above  mentioned,  where  these  margins  are 
actually  sligmatic  for  almost  their  whole  length,  and  in  Schizandra, 
where  the  stigmatic  surface  (known  by  its  papillose  cells  or  other 
surface  exposed  directly  to  the  air,  without  any  epidermis)  begins 
externally  on  the  ventral  edge  of  the  pistil,  just  above 
the  point  where  the  ovules  are  attached  within  (Fig. 
375).  In  the  Pseony,  in  Isopyrum  (Fig.  374),  and  a 
great  number  of  instances,  the  stigma  consists  of  two 
crested  ridges  or  parallel  lines  running  down  the  inner 
face  of  the  style  ;  and  in  a  still  larger  number  of  cases 
(as  in  nearly  all  Caryophyllacese  and  a  part  of  Malva- 
ceae), a  continuous 'Stigmatic  surface  extends  down  this 
face  of  the  style  (Fig.  384).  Such  unilateral  stigmas 
we  accordingly  take  to  be  the  normal  form  ;  and  say 
that,  while  the  united  margins  of  the  typical  leaf  composing  the 
ventral  suture  are  turned  inwards  into  the  cell  of  the  ovary  to 
hear  the  ovules^  in  the  simple  style  they  are  exposed  externally  to 
form  the  stigma.     Where  the  stigma  is  terminal,  or  occupies  only 

the  apex  of  the  style,  we  suppose 
that  these  margins  are  infolded  in 
the  style  also,  and  form  in  its  in- 
terior the  loose  conducting  tissue 
through  which  a  communication  is 
established  between  the  terminal 
stigma  and  the  interior  of  the  ova- 
ry. The  double  nature  of  the 
stigma  (one  lamella  of  which  cor- 
responds to  each  margin  of  a  leaf)  is  still  evident  in  the  two 
lobes  which  the  terminal  stigma  exhibits  in  many  simple  pistils, 
as  in  Hydrastis  (Fig.  376),  and  Actsea  (Fig.  377). 

542.  The  ovary  contains  only  Ovules,  or  bodies  destined  to 
become  seeds  after  fertilization  (420).  These,  in  all  ordinary 
cases,  are  borne  on  the  part  which  represents  the  margins  of  the 
transformed   leaf.      They  are  in  some  sort  analogous   to   buds, 


FIG.  374.  A  ventral  view  of  a  pistil  of  Isopyrum  biternatum,  showing  the  double  stigma; 
the  ovary  cut  across,  showing  the  two  rows  of  ovules. 

FIG.  375.  Vertical  section  of  a  pistil  of  Schizandra  coccinea ;  a  side  view.  376.  Pistil  of 
Hydrastis.  377.  Pistil  of  Actaea  rubra,  cut  across,  so  as  to  show  the  interior  of  the  ovary  (the 
ventral  suture  turned  towards  the  observer). 


THE    FLOWER. 

which  are  occasionally  developed  on  the  margins  of  leaves  (as  in 
the  well-known  case  of  Bryophyllum,  Fig.  271).  Since  both 
margins  of  the  infolded  leaf  may  bear  ovules,  the  latter  are  nor- 
mally arranged  in  two  rows  (one  for  each  margin)  on  the  inner 
or  ventral  suture ;  as  is  seen  in  Fig.  263,  374,  377.  The  ovule- 
bearing  portion  of  the  ventral  suture,  which  often  forms  a  ridge  or 
crest  projecting  more  or  less  into  the  cavity  of  the  ovary,  is  named 

543.  The  Placenta.  As  it  corresponds  with  the  ventral  suture, 
and  is  in  fact  a  part  of  it,  or  a  cellular  growth  from  it,  it  is  always 
placed  next  the  axis  of  the  flower ;  as  is  evidently  the  case  when 
two,  three,  or  more  pistils  are  present  (Fig.  379  -  383).  Each  pla- 
centa necessarily  consists  of  two  parts,  one  belonging  to  each  of 
the  confluent  margins  of  the  transformed  leaf.  It  therefore  is  fre- 
quently two-lobed,  or  of  two  diverging  lamella  (Fig.  263).  The 
ovules  vary  greatly  in  number ;  being  sometimes  very  numerous 
and  in  several  rows  on  a  broad  placenta,  as  in  the  May- Apple 
(Podophyllum)  ;  sometimes  in  two  normal  rows  occupying  the 
whole  length  of  the  ventral  suture,  as  in  the  Larkspur,  Columbine, 
Actsea  (Fig.  377),  &c. ;  sometimes  reduced  to  one  row  in  appear- 
ance, as  in  the  Pea,  where  on  inspection  they  will  be  found,  how- 
ever, to  be  alternately  attached  to  each  lamella  of  the  placenta,  that 
is,  to  each  margin  of  the  leaf:  again,  they  occupy  only  its  middle, 
base,  or  summit,  where  they  are  often  reduced  to  a  definite  num- 
ber, to  a  single  pair  (Fig.  375),  or  to  a  single  one  (Fig.  316). 

544.  When  the  pistils  are  distinct  or  uncombined,  they  are  said 
to  be  apocarpous ;  when  they  are  united,  and  form  a  compound 
pistil,  they  are  syncarpous.  We  have  carefully  to  distinguish  be- 
tween the  simple  pistil^  which  represents  a  single  member  of  the 
gynsecium  (419),  and  the  compound  pistil^  which  answers  to  the 
whole  circle  coalescent  into  one  body.  To  subserve  this  purpose, 
botanists  have  coined  the  name  of 

545.  The  Carpel  or  Carpidium.  This  name  designates  an  individual 
member  of  the  gynsecial  circle,  whether  it  occur  as  a  separate  or 
simple  pistil,  or  as  one  of  the  elements  of  a  compound  pistil.  It  is 
in  the  latter  case  that  the  name  is  principally  needful.  All  degrees 
of  union  of  the  carpels  may  be  observed,  from  the  mere  cohesion 
of  their  contiguous  inner  angles,  to  the  perfect  consolidation  of  the 
ovaries  while  the  styles  remain  distinct,  as  in  Spergularia  (Fig. 
387),  or  of  the  latter  also.  Rarely  the  stigmas  or  styles  are  united 
while  the  ovaries  remain  distinct,  as  in  Asclepias  and  Apocynum 


THE    COMPOUND    PISTIL. 


301 


(Ord.  Asclepiadacese  and  Apocynacese).  Numerous  illustrations 
of  ali  the  varied  forms  are 
given  in  the  systematic  part 
of  this  volume.  The  an- 
nexed diagrams  represent, 
Fig.  378,  379,  three  dis- 
tinct but  approximated  pis- 
tils;  Fig.  380,  381,  three 
pistils  with  their  ovaries 
coalescent;  and  Fig.  382, 
383,  three  pistils  with  their 
styles  as  well  as  their  ova- 
ries united  into  one. 

546.  The  Compound  Pistil. 

From  these  illustrations  the  regular  structure  of  the  compound 
pistil  is  readily  seen,  at  least  as  to  the  more  common  and  normal 
case,  namely,  where  the  cross-section  displays  two  or  more  cells^ 
or  separate  cavities.  For  it  is  evident  that,  if  the  contiguous  parts 
of  a  whorl  of  three  or  more  carpels  cohere,  the  resulting  compound 
ovary  will  have  as  many  cavities,  or  cells,  as  there  are  carpels  in 
its  composition,  and  the  placentae  will  all  be  brought  together  in 
the  axis ;  as  is  shown  in  Fig.  381,  383,  in  Fig.  291,  and  in  the  gy- 
nsecium  of  Fig.  306,  as  compared  with  Fig.  284,  &c. 

547.  The  partitions,  or  Dissepiments,  which  divide  the  com- 
pound ovary  into  cells,  are  evidently  composed  of  the  united  con- 
tiguous portions  of  the  walls  of  the  carpels.  These  necessarily 
consist  of  two  layers,  one  belonging  to  each  carpel ;  they  are 
always  vertical,  and  are  equal  in  number  to  the  carpels  of  which 
the  compound  pistil  is  constructed. 

548.  A  single  carpel,  therefore,  has  no  proper  dissepiment.  It 
is,  however,  sometimes  divided  by  spurious  partitions,  separating 
the  cavity  into  separate  cells  or  joints,  placed  one  above  another, 
as  in  some  species  of  Cassia,  in  Desmodium,  &c.  (Fig.  440,  441) ; 
or  even  by  a  vertical  false  dissepiment  produced  by  the  introflex- 
ion  of  the  inner  or  placental  suture,  as  is  partially  the  case  in  some 
species  of  Phaca  and  Oxytropis  (Fig.  445) ;   or  by  a  projection 

FIG.  378.  A  whorl  of  three  pistils,  the  line  which  passes  down  the  inner  side  representing 
the  ventral  suture.  379.  A  cross-section  of  their  ovaries,  showing  the  two  rows  of  ovules,  oc- 
cupying the  inner  angle,  or  ventral  suture.  380.  A  whorl  of  three  pistils,  their  ovaries  unile<l. 
331.  A  cross-section  of  the  same.  382.  Three  pistils,  with  their  styles  also  united  quite  to  the 
Bummit.    333.  A  cross-section  of  the  united  ovaries. 

26 


302  THE    FLOWER. 

from  the  dorsal  suture,  as  in  the  Flax  (Ord.  Linacese),  the  Service- 
Berry,  and  many  species  of  Vaccinium  ;  or  by  its  introflexion,  as 
in  Astragalus  (Fig.  444). 

549.  A  compound  ovary  of  two  cells,  or  locuH,  is  hilocular ;  of 
three,  trilocular ;  of  four,  quadrilocular  ;  of  five,  quinquelocular ; 
and  so  on.  If  of  several  without  reference  to  the  number,  it  is 
said  to  be  plurilocular,  or  multilocular ;  the  former  name  being 
used  when  the  cells  are  comparatively  few,  the  latter  when  more 
numerous.     We  may,  however,  have  a 

550.  Uuilocular  Compound  Pistil,  where  the  ovary,  although  com- 
posed of  two  or  more  carpels,  is  yet  one-celled^  that  is,  has  a  single 
CLivity.  The  cases  of  the  sort  are  of  two  principal  kinds,  namely, 
first, 

551.  With  a  free  Placenta  in  the  Axis,  as  in  the  Primrose  Fam- 
ily (Ord.  Primulacese),  and  in  a  large  part  of  the  Chickweed  and 
Pink  Family,  as  shown  in  Fig.  384.     This  is  usually  explained  on 

the  supposition  that  the  dissepiments  are  obliterated 
or  torn  away  by  the  expansion  during  the  growth 
of  the  ovary,  these  alone  being  wanting  to  com- 
plete the  structure  of  the  normal  compound  ovary 
already  described,  as  will  be  seen  by  comparing 
the  diagram.  Fig.  387,  with  Fig.  383.  This  is 
demonstrably  the  true  explanation  in  the  Chick- 
weed  and  Pink  Family ;  for  the  dissepiments,  or 
vestiges  of  them,  may  be  detected  at  an  early 
stage,  and  sometimes  at  the  base  of  the  full-grown 
ovary  ;  while  certain  plants  of  the  same  family,  of  otherwise  iden- 
tical structure,  retain  the  partitions  even  in  the  ripe  pod.  Other 
cases,  however,  especially  where  there  are  a  few  ovules,  or  even  a 
single  one,  as  in  Thrift  (Ord.  Plumbaginacese),  arising  from  the 
base  of  the  cell,  are  more  properly  referred  to  the  other  kind  of 
unilocular  compound  pistil,  namely,  that 

552.  With  Parietal  Placeutation.  If  we  suppose  a  circle  of  three 
carpellary  leaves,  with  their  margins  turned  inwards,  yet  not  so  as 
to  reach  the  axis,  to  cohere  merely  by  their  contiguous  inflexed 
portions,  a  one-celled  tricarpellary  ovary  would  result,  with  three 
imperfect  dissepiments  projecting  into  the  cavity,  but  not  dividing 
it  into  distinct  cells  (as  in  the  diagram,  Fig.  385).     The  placentae 

FIG.  334.    Vertical  section  through  the  compound  tricarpellary  ovary  of  a  plant  of  the 
Chickweed  Family  (Spergularia  rubra),  showing  the  free  central  placenta. 


PARIETAL    PLACENTATION. 


303 


are  here  borne  upon  the  extremity  of  the  imperfect  dissepiments, 
which,  if  somewhat 
prolonged,    would 
meet  and  unite  in 
the  centre,  so  as  to 

present  the  regular     \    QP      ^        V     _^     J 
three-celled  struc- 
ture   (as    in    Fig. 

383).  This  will  be  evident  on  comparing  the  pod  of  the  Common 
St.  John's- wort  (figured  under  Ord.  Hypericacese),  which  is  com- 
pletely three-celled  with  the  placentse  united  in  the  axis,  with  the 
ovary  of  another  species  (Fig.  388),  where  the 
three  placentae  touch  in  the  centre  without  co- 
hering, and  with  the  full  grown  pod  of  the  last 
(Fig.  389),  where  they  are  drawn  asunder  by 
the  expansion  of  the  growing  pod,  and  remain 
attached  only  to  its  walls,  borne  on  three  slight 
introflexions,  which  stand  in  the  place  of  dissepi- 
ments. Parnassia  affords  a  similar  instance, 
only  there  are  usually  four  such  placentse  in- 
stead of  three  (Fig.  304,  the  centre  of  which 
represents  a  cross-section  of  the  4-carpellary 
ovary).  These  instances  bring  us  to  the  fre- 
quent case  in  which  we  may  say  that  the  leaves 
of  the  gyngecial  verticil,  placed  merely  in  apposition,  as  in  valvate 
EBstivation  (499),  directly  cohere  into  one  circle  by  their  respective 
contiguous  margins ;  which,  being  barely  induplicate,  form  pla- 
centae which  are  borne  directly  on  the  walls.  This  is  shown  in 
the  diagram.  Fig.  386,  representing  a  cross-section  of  three  carpels 
thus  combined  into  a  compound  one-celled  ovary,  without  any  ap- 
pearance of  dissepiments.  Thus  borne  upon  the  walls,  instead  of 
in  the  axis,  of  the  compound  ovary,  the  placentse  are  said  to  be 
'parietal.  Examples  of  the  kind  with  a  tricarpellary  ovary  are 
furnished  by  many  Hypericums,  by  the  Violet  Family,  the  Cistus 


FIG.  395  -  387.  Diagrams  illustrating  parietal  and  free  central  placentation.  385,  Cross- 
section  of  an  ovary  composed  of  three  united  carpels,  wiiere  the  introflexed  portions  do  not 
reach  the  centre.  386.  Section  of  a  similar  ovary,  except  that  the  placental  margins  unite 
without  any  introflexion  (placentae  strictly  parietal).  387.  Section  of  a  tricarpellary  ovary, 
with  a  free  central  placenta,  produced  by  the  obliteration  of  the  dissepiments. 

FIG.  388.  Magnified  cross-section  of  the  ovary  of  Hypericum  graveolens.  389,  Enlarged 
cross-section  of  the  mature  pod  of  the  same,  where  the  placentse  become  strictly  parietal. 


304  THE    FLOWER. 

Family  (Ord.  Cistacese),  Drosera  (Fig.  390),  &c.  Also,  in  an 
ovary  of  two  carpels,  by  the  Caper  Family  (Ord.  Capparidacese), 
the  Fumitory  Family  (Fig.  298),  the  Gooseberry 
(Ord.  Grossulaceae),  dz;c. 

553.  An  ovary  with  parietal  placentae  is  neces- 
sarily one-celled  ;  except  it  be  divided  by  an  anoma- 
lous partition,  such  as  that  of  Cruciferous  plants,  &c. 

554.  A  compound  pistil  of  this  kind  may  have  the 
sutures  ovuliferous,  or  develope  placentae,  only  at 
some  particular  part,  as  at  the  summit  or  the  base 
of  the  cell ;  and  there  few  or  only  solitary  ovules 
may  be  developed,  as  in  the  Thrift  (Ord.  Plumba- 
ginacese),  in  Compositse,  &c.,  which  reduces  the 
case  to  the  greatest  simplicity.  The  confluence  of  two  or  more 
basilar  parietal  placentfe  will  account  for  the  free  central  placen- 
tation  in  cases  where  no  dissepiments  are  discernible  at  an  early 
period,  as  in  the  Primrose  Family. 

555.  It  will  be  seen  that  parietal  placentae  are  necessarily  dou- 
ble, like  the  placenta  of  a  simple  ovary,  or  of  each  carpel  of  a 
compound  plurilocular  ovary  ;  but  with  this  difference,  that  in 
these  cases  the  two  portions  belong  to  the  two  margins  of  the  same 
carpel ;  while  in  parietal  placentae  they  are  formed  from  the  coalcs- 
cent  margins  of  two  adjacent  carpels.  This  will  readily  appear 
on  comparing  the  diagrams.  Fig.  379,  381,  whh  Fig.  385,  386. 

556.  The  number  of  carpels  of  which  a  compound  ovary  con- 
sists is  indicated  by  the  number  of  true  dissepiments  when  these 
exist  (547) ;  or  by  the  number  of  placentae,  when  these  are  parie- 
tal (552) ;  or  by  the  number  of  styles  or  stigmas,  when  these  are 
not  wholly  united  into  one  body.  Thus  a  simple  pistil  has  a  single 
cell,  a  single  placenta,  and  a  single  style.  A  pistil  of  two  carpels 
may  be  two-celled,  with  two  placentae,  two  styles,  &c. 

557.  There  are,  however,  some  exceptions  which  qualify  these 
statements  :  —  1.  Each  placenta  being  a  double  organ  (555),  it  oc- 
casionally happens  that  the  two  portions  are  separated  more  or 
less,  as  in  Orobanchaceous  plants,  where  a  dicarpellary  ovary  ap- 
pears on  this  account  to  have  four  parietal  placentae  ;  either  ap- 
proximate in  pairs  (as  in  our  Cancer-root,  Conopholis),  or  equidis- 
tant (as  in  Aphyllon).     2.  Analogous  to  this  is  the  case  where 

FIG.  390,  Pistil  of  Drosera  filiformibus,  with  three  2-parted  styles  ;  the  ovary  cut  across, 
showing  three  parietal  placentae. 


PLACENTATION.  305 

the  two  constituent  elements  of  the  stigma  (the  only  essential  part 
of  the  style)  separate  into  two  half-stigmas ;  a  tendency  to  which 
is  seen  in  Fig.  376,  377,  and  which  is  carried  out  in  most  spe- 
cies of  Drosera  (Fig.  390).  The  stigma,  no  less  than  the  placenta, 
belongs  to  the  margins  of  the  infolded  leaf  (541),  these  margins 
being  ovuliferous  in  the  ovary  and  stigmatiferous  in  the  style  ;  as 
Mr.  Brown,  the  most  profound  botanist  of  this  or  any  age,  has 
clearly  shown.  These  two  constituent  portions  of  the  style  or 
stigma  are  usually  combined  ;  but  are  not  unfrequently  separate, 
either  entirely  or  in  part,  as  in  Euphorbiaceous  plants,  in  Grasses, 
and  especially  in  Drosera,  where  there  are  consequently  twice  as 
many  nearly  distinct  styles  as  there  are  parietal  placentae  in  the 
compound  ovary.  If  the  two  component  parts  of  the  style  of  each 
carpel  were  reunited  into  one,  in  the  usual  manner,  their  number 
would  equal  the  placentae,  and  their  position  would  be  alternate 
with  the  latter.  But  since,  in  parietal  placentation,  each  half-pla- 
centa is  confluent,  not  with  its  fellow  of  the  same  carpel,  but  with 
the  contiguous  half -placenta  of  the  adjacent  carpel  (555),  it  were 
surely  no  greater  anomaly  for  the  elements  of  such  half-stigmas 
as  those  of  Drosera  (Fig.  390)  to  follow  the  same  course.  This 
is  precisely  what  takes  place  in  Parnassia,  and  in  other  cases 
where  the  stigmas  are  opposite  the  parietal  placentae ;  —  cases 
which  were  thought  to  be  very  anomalous,  merely  on  account  of 
the  adoption  of  a  false  principle  (that  of  the  necessary  alternation 
of  the  stigmas  and  placentae),  but  which  are  really  no  more  so 
than  the  parietal  placentation  itself.  The  division  of  the  style 
in  such  cases  furnishes  further  examples  of  collateral  chorisis. 
Sometimes  the  simple  style  is  repeatedly  forked  in  this  way,  or  cut 
into  a  fringe  at  the  summit,  as  in  Turnera,  and  the  short  lobes  of 
the  compound  style  in  Dionaea.  3.  Furthermore,  the  production 
of  ovules  is  not  always  restricted  to  what  answers  to  the  margins 
of  the  carpellary  leaves.  In  the  Poppy,  the  whole  surface  of  the 
long,  imperfect  partitions  is  covered  with  ovules  ;  in  Butomus,  they 
are  borne  over  the  whole  internal  face  of  each  carpel,  and  in  the 
Water-Lilies  over  the  whole  surface  (Fig.  268),  except  the  inner 
angle  of  each  cell,  where  alone  they  normally  belong.  Reduced 
to  two  in  the  allied  Water-Shield  (Brasenia,  Ord.  Cabombaceae), 
the  ovules  grow  from  the  dorsal  suture,  or  the  midrib  of  the  car- 
pellary leaf  alone !  And  in  Cabomba  itself  we  usually  find  its 
three  ovules,  one  on  the  dorsal  and  one  on  the  ventral  suture,  and 
26* 


306  THE    FLOWER 

the  third  on  some  variable  part  of  the  face  of  the  cell  in  the  vicin- 
ity of  either  suture.  In  Obolaria,  a  compound  unilocular  ovary  is 
ovuliferous  over  the  whole  wall  of  the  cell.* 

558.  When  the  styles  are  separate  towards  the  summit,  but 
united  below,  they  are  usually  described  as  a  single  organ ;  which 
is  said  to  be  parted^  clefts  lobed,  &c.,  according  to  the  extent  of 
cohesion.  This  language  was  adopted,  as  in  the  case  of  leaves 
(281)  and  floral  envelopes  (461),  long  before  the  real  structure 
was  understood  :  but,  as  it  involves  an  erroneous  idea,  the  expres- 
sions. Styles  distinct ;  united  at  the  base  ;  united  to  the  middle,  or 
summit,  &c.,  as  the  case  may  be,  should  be  employed  in  preference. 

559.  A  few  casual  exceptions  occur  to  the  general  rule  that 
ovules  and  seeds  are  both  produced  and  matured  within  an  ovary, 
namely,  in  a  closed  carpeliary  leaf  or  set  of  combined  carpellary 
leaves.  In  the  Blue  Cohosh,  Leontice  (Caulophyllum)  thalictroi- 
des,  the  ovules  rupture  the  ovary  soon  after  flowering,  and  the 
seeds  become  naked  ;  and  in  the  Mignonette  they  are  imperfectly 
protected,  the  ovary  being  open  at  the  summit  from  an  early  pe- 
riod. In  all  such  cases,  however,  the  pistil  is  formed  and  the 
ovules  are  fertilized  in  the  ordinary  way. 

560.  GynsBcium  of  Gymnospermous  Plants.  A  far  more  important 
and  remarkable  exception  is  presented  by  two  natural  families, 

the  Coniferse  (Pines,  Firs,  &c.,  Fig. 
391-402),  and  the  Cycadacece  (Cy- 
cas,  Zamia,  Fig.  403).  Here  the 
pistil,  as  likewise  the  whole  flower, 
is  reduced  to  the  last  degree  of  sim- 
plicity ;  each  fertile  flower  consisting 
merely  of  an  open  carpellary  leaf,  in  place  of  a  pistil,  in  the  form 

*  These  various  points  are  elucidated  by  Mr.  Brown,  in  PlantcR  Javanica 
Rariores,  pp.  107-112,  in  two  notes  which  apparently  are  not  sufficiently 
studied  by  many  English  botanists.  —  All  placentation  is  very  differently  ex- 
plained by  those  who  adopt  the  hypothesis  of  Schleiden  and  others.  Accord- 
ing to  this  new^view,  as  buds  regularly  arise  from  the  axils  of  leaves  and  from 
the  extremity  of  the  stem  or  axis,  and  only  in  some  exceptional  and  abnormal 
cases  from  the  margins  or  surface  of  leaves,  so  ovules  are  considered  to  arise 
from  the  axis  of  the  flower,  like  terminal  buds,  or  from  the  axils  of  the  car- 
pellary leaves,  like  axillary  buds.     Thus,  placentae  are  supposed  to  belong  to 

FIG.  391.  A  carpellary  scale  from  the  ament  of  a  Larch,  the  upper  side  turned  to  the  eye, 
showing  the  pair  of  ovules  at  its  base.  392.  The  same  in  fruit,  reduced  in  size;  one  of  the 
winged  seeds  still  attached ;  the  other,  393,  separated. 


IN    GYMNOSPERMOTJS    PLANTS.  307 

of  a  scale,  as  in  Fig.  391,  or  sometimes  of  a  different  shape  (Fig. 


407),  which  bears  two  or  more  ovules  upon  some  part  of  its  mar- 


the  axis,  and  not  to  the  carpellary  leaves ;  and  a  one-celled  ovary,  with  one 
or  more  ovules  arising  from  the  base  of  the  cell,  would  nearly  represent  the 
typical  state  of  the  gyncecium.  This  theory,  which  the  intelligent  student 
may  easily  apply  in  detail,  offers  the  readiest  explanation  of  free  central  pla- 
centation,  especially  in  such  cases  as  Primula,  «&c.,  where  not  the  slightest 
trace  of  dissepiments  is  ever  discoverable.  It  must  be  admitted  that  the  mon- 
strosities which  occur  in  Primula,  and  some  other  plants  with  free  central 
placentation,  favor  this  new  view.  It  is  also  perfectly  applicable  to  ordinary 
central  placentation;  where  we  have  only  to  suppose  the  cohesion  of  the  in- 
flexed  margins  of  the  carpellary  leaves  with  a  central  prolongation  of  the  axis 
or  receptacle  which  bears  the  placentae.    But  in  case  of  parietal  placentation, 

FIG,  394.  Carpellary  scale  of  Cupressus  sempervirens  (the  true  Cypress),  seen  from  within, 
and  showing  the  numerous  orlhotropous  ovules  that  stand  on  its  base.  395.  Branch  of  Abies 
Canadensis  (Hemlock  Spruce),  with  lateral  staminate  flowers,  and  a  fertile  strobile.  396.  Stam- 
inate  ament,  magnified.  397.  Carpellary  scale  of  a  fertile  ament,  with  its  bract.  398.  Simi- 
lar fertile  scale,  more  magnified  and  seen  from  within ;  showing  the  two  ovules  adherent  to  its 
base:  one  of  them  (the  left)  laid  open.  399.  The  scale  in  front,  nearly  of  the  natural  size,  its 
inner  surface  occupied  by  the  two  seeds.  400.  Polycotyledonous  embryos  of  Abies  and  Cypres.?. 
401.  Vertical  section  of  one.    402.  Strobile  of  Taxodium  distichum  (Suborder  Cupressiueae). 


3^  '  THE    FLOWER. 

gin  or  upper  surface.     The  ovules,  therefore,  instead  of  being  in- 


closed  in  an  ovary,  and  acted  upon  by  the  pollen  through  the  in- 


the  advocates  of  this  theory  are  obliged  to  suppose  that  the  axis  divides  within 
the  compound  ovary  into  twice  as  many  branches  as  there  are  carpels  in  its 
composition,  and  that  these  branches  regularly  adhere,  in  pairs,  one  to  each 
margin  of  all  the  carpellary  leaves.  Its  application  is  attended  with  still 
greater  difficulties  in  the  case  of  simple  and  uncombined  pistils,  where  the 
ovules  occupy  the  whole  inner  suture,  which  are  doubtless  justly  assumed  as 
the  regular  and  typical  state  of  the  gynaecium  ;  but  to  which  the  new  hypoth- 
esis can  be  adapted  only  by  supposing  that  an  ovuliferous  branch  of  the  axis 
enters  each  carpel,  and  separates  into  two  parts,  one  cohering  with  each  mar- 
gin of  the  metamorphosed  leaf.  This  vievv,  however,  not  only  appears  very 
improbable,  but  may  be  disproved  by  direct  observation,  as  it  has  been  most 
completely  by  those  monstrosities  in  which  an  anther  is  changed  into  a  pistil, 
or  even  one  part  of  the  anther  is  thus  transformed  and  bears  ovules,  while  the 
other,  as  well  as  the  filament, remains  unchanged;  —  a  case  where  the  forma- 

FIG.  403.  Zamia  integrifolia  (the  Coontie  of  Florida).  404.  Section  of  the  sterile  ament. 
405.  One  of  its  scales  detached,  bearing  scattered  anthers.  406.  Fertile  ament,  from  which  a 
quarter-section  is  removed.  407.  A  pistillate  flower,  consisting  of  two  ovules  pendent  from 
the  thickened  summit  of  the  carpellary  scale.  408.  A  drupaceous  seed,  from  which  a  part  of 
the  pulpy  outer  portion  is  removed.  409.  Vertical  section  through  the  seed  (of  the  natural  size), 
showing  the  pulpy  outer  coat,  the  hard  inner  integument,  the  albumen,  and  the  embryo. 


THE    OVULE.  309 

tervention  of  a  stigma,  are  naked  and  exposed, —  except  as  they 
are  nnore  or  less  covered  in  Pines,  Firs,  &c.,  by  the  imbrication  of 
the  carpellary  scales  into  a  sort  of  ament  or  cone  (as  in  Fig.  176, 
&c.),  —  and  are  fertilized  by  the  direct  application  of  the  pollen. 
Their  seeds,  accordingly,  are  destitute  of  a  pod,  or  any  similar  in- 
closure.  On  this  account  they  have  received  the  name  of  Gym- 
NosPERMous  Plants  (111) ;  literally,  plants  with  naked  seeds. 

Sect.  VIII.     The  Ovule. 

561.  Ovules,  the  rudiments  of  future  seeds  (420),  at  first  ap- 
pear like  minute  pulpy  excrescences  of  the  placenta;  but  long 
before  the  flower  expands  they  have  acquired  a  regular,  and  gen- 
erally round  or  oval  form.  They  are  attached  to  the  placenta  by 
one  extremity,  either  directly,  or  by  a  short  stalk  called  the  Fu- 
niculus^ or  Podosperm  (Fig.  413,  414).  As  to  number,  they  vary 
from  one  in  each  ovary,  or  in  each  cell  of  the  compound  ovary,  to 
several  or  many  upon  each  placenta.  In  the  former  case,  they  are 
said  to  be  solitary ;  in  the  latter,  they  are  definite  when  their  num- 
ber is  uniform  and  not  remarkably  great,  and  indefinite^  when 
they  are  too  numerous  to  be  readily  counted. 

562.  As  to  situation  and  direction  with  respect  to  the  cavity  that 
contains  them,  ovules  are  said  to  be  erect  when  they  arise  from 
the  very  bottom  of  the  ovary  ;  ascending,  when  fixed  to  the  pla- 
centa above  the  base  and  directed  obliquely  upwards ;  horizontal, 
when  they  project  from  the  side  of  the  cell,  without  turning  either 
upwards  or  downwards  (Fig.  263) ;  pendulous,  when  their  direc- 
tion is  downwards ;  and  suspended,  when  they  arise  from  the  sum- 

tion  of  the  placenta  from  a  process  of  the  axis  is  out  of  the  question.  This 
hypothesis  is,  therefore,  entirely  untenable  as  a  general  theory  ;  and  whether 
it  affords  a  correct  explanation  of  any  form  of  central  or  basilar  placentation 
must  be  left  for  further  observation  to  determine.  VVe  will  only  remark,  that 
even  the  appearance  of  a  placenta  or  ovuliferous  body  in  the  apparent  axil  of 
a  carpellary  leaf  no  more  proves  that  the  body  in  question  belongs  to  the  axis, 
than  that  the  appendage  before  the  petals  of  Parnassia  and  the  American 
Linden,  or  the  stamen  of  a  Rhamnus  or  Vitis,  represents  the  axis  of  a  branch 
instead  of  a  leaf.  As  to  the  terminal  naked  ovule  of  the  Yew,  where  the 
structure,  on  any  view,  is  reduced  to  the  greatest  possible  simplicity,  it  is 
surely  as  probable  that  it  answers  to  the  earliest  formed,  or  foliar^  portion  of 
the  last  phyton,  here  alone  developed,  as  to  the  cauline  part,  which  is  so  com- 
monly suppressed  in  the  flower. 


310  THE    FLOWER. 

mit  of  the  ovary  and  hang  perpendicularly  in  the  cavity  (Fig.  316). 
In  the  Thrift  (Ord.  Plurnbaginacese),  and  in  the  Sumach,  the  ovule 
is  singularly  pendent  from  an  ascending  funiculus.  These  terms 
are  applicable  to  the  seed  as  well  as  to  the  ovule. 

563.  As  to  its  structure  and  formation,  the  ovule  appears  as  a 
mere  excrescence,  or  papilla,  of  soft  and  homogeneous  parenchyma, 
which  soon  acquires  a  definite  form.  This  Nucleus,  as  it  is  called, 
is  the  essential  part  of  the  organ ;  in  the  Mistletoe  it  actually  con- 
stitutes the  whole,  its  ovule  having  no  integuments  of  its  own.  A 
hollow  place  is  formed  in  its  interior  about  the  time  of  flowering, 
in  which  the  embryo  at  length  appears.  Most  ovules,  however,  in 
the  course  of  their  growth  acquire  an  envelope,  or  more  commonly 
two  envelopes.  Only  one  envelope  is  seen  in  the  ovule  of  the  Wal- 
nut, where,  after  the  nucleus  is  formed  and  has  assumed  its  ovate 
shape,  a  circular  ring  appears  around  its  base,  which  gradually 
enlarges  into  a  sheath,  but  at  length  covers  it  like  a  sac,  which, 
however,  remains  open  at  the  apex.  This  orifice,  which  leads  to 
the  nucleus,  and  through  which,  indeed,  the  nucleus  often  pro- 
trudes, is  called  the  Foramen  or  the  MicRorYLE.  In  far  the 
greater  number  of  cases,  a  second  envelope  is  formed  outside  of 
the  first,  beginning  in  the  same  way,  though  always  later  than  the 
inner  one,  which,  however,  it  eventually  overtakes  and  incloses. 
The  outer  envelope,  when  both  are  present,  becomes  the  exterior 

integument    or    testa   of    the 

4.0  413  <-' 

seed ;  and  the  inner,  its  teg- 

415    u\\\>>^^    men   or  inner  coat.      Mirbel 

named  the  exterior  coat  of  the 

xsy         ovule  the  Primine,  and  the  in- 

W^  terior  the  Secundine,  names 

//|l'ilX\      /'~^        ^^^     which  are  attended  with  the 

rJ-  lill     I      1^    ^^SM     objection  that  the  secundine  or 

^  wJ)     \    r"^      ^Ti      second  coat  is  actually  older 

d      \^.._  ^         \j  g|^      x\\^n  the  primine  or  first  coat 

*"  ^'^  "*      in  the  order  of  position.     Both 

sacs  are  open  at  the  apex,  and  the  summit  of  the  nucleus  points 


FIG.  410.  An  orthotropous  ovule.  411.  Longitudinal  section  of  the  same,  more  magnified: 
a,  the  primine;  6,  the  secundine;  c,  the  nucleus;  d,  the  chalaza.  412.  An  amphitropoua 
ovule.  413.  Three  anatropous  ovules,  with  their  funiculi,  attached  to  a  portion  of  the  placenta. 
414.  One  of  the  same,  more  highly  magnified,  exhibiting  its  cellular  structure.  415.  A  campy- 
lotropous  ovule. 


THE    OVULE.  311 

directly  towards  the  apertures.  The  orifice  or  foramen  of  the 
exterior  integument  is  called  the  Exostome  (or  outer  mouth),  that 
of  the  interior,  the  Endostome  (or  inner  mouth).  The  coats  of 
the  ovule  and  the  nucleus  are  distinct  and  unconnected,  except  at 
the  base,  or  point  of  attachment  to  the  funiculus,  where  they  are 
all  perfectly  confluent :  this  point  of  union  receives  the  name  of 
the  Chalaza  (Fig.  411,  d). 

564.  Through  the  funiculus  and  chalaza  the  ovule  derives  its 
nourishment  from  the  placenta ;  through  the  opening  at  the  sum- 
mit, the  nucleus  receives  the  influence  of  the  pollen,  which  results 
in  the  production  of  the  embryo. 

565.  Our  description  applies  to  the  complete  ovule  in  its  sim- 
plest form,  where  no  change  in  the  position  of  parts  takes  place 
during  its  growth,  the  chalaza  remaining  next  the  placenta,  with 
which  the  funiculus  directly  connects  it,  while  the  apex,  represent- 
ed by  the  foramen,  or  orifice  of  the  coats,  is  at  the  opposite  ex- 
tremity (as  in  Fig.  410).  Such  an  ovule,  not  being  curved  or 
turned  from  its  normal  direction,  is  called  atropous  (literally,  not 
turned),  or  usually  orlhotropous  (straight).  This  simple  orthotro- 
pous  form  occurs  in  the  Cistus  Family  (Ord.  Cistacese),  and  the 
Polygonum  Family  (Ord.  Polygonaceae),  and  in  many  others. 

566.  In  the  greater  number  of  cases,  however,  a  change  of  rela- 
tive position  takes  place  during  the  development  of  the  ovule  ;  con- 
sisting either  in  its  complete  inversion  upon  the  funiculus  that  bears 
it,  so  that  the  orifice  or  apex  is  brought  down  by  the  side  of  the 
stalk  and  points  towards  the  placenta,  while  the  chalaza  looks  in  the 
opposite  direction  (as  in  Fig.  413, 414,  and  also  in  Fig.  263,  where 
such  ovules  are  seen  in  their  natural  position  in  the  ovary) ;  or 
else  the  ovule  curves  upon  itself,  and  thus  brings  down  the  apex 
near  the  funiculus  (as  in  Fig.  416).  In  the  former  case,  the  ovule 
is  anatropous,  or  inverted ;  in  the  latter,  it  is  campylotropous^  or 
curved.  Campylotropous  ovules  are  found  in  the  Mignonette,  in 
all  Cruciferous  and  Caryophyllaceous  plants,  and  in  many  others  ; 
but  the  anatropous  form  is  by  far  the  most  common  of  all. 

567.  In  anatropous  ovules,  the  funiculus  coheres  firmly  with 
that  part  of  the  surface  which  is  applied  to  it ;  and  in  the  ripe  seed 
breaks  away  at  the  point  where  it  is  free  from  the  integument,  to 
which  the  adherent  portion  remains  attached.  The  latter  receives 
the  name  of  Raphe  ;  and  appears  in  the  form  of  a  ridge,  cord,  or 
line,  passing  from  the  Hilum  (as  the  scar  left  by  the  breaking 


312  THE    FLOWER. 

away  of  the  funiculus  from  the  seed  is  tei;«iecl)  to  the  chalaza, 
maintaining  the  communication  between  the  interior  of  the  ovule 
or  seed  and  the  placenta.  The  raphe  is  only  found  in  the  anatro- 
pous  ovule,  and  serves  to  distinguish  it ;  since  in  all  others  the" 
hilum  or  scar  exactly  corresponds  to  the  chalaza,  while  in  this 
the  two  occupy  opposite  extremities  of  the  seed ;  the  chalaza, 
which  is  the  real  base,  being  by  this  inversion  situated  at  the  ap- 
parent apex,  while  the  micropyle,  or  organic  apex,  is  found  next 
the  hilum,  or  the  apparent  base.  This  is  perfectly  simple  on  the 
supposition  that  an  anatropous  ovule  is  produced  by  the  mere 
adhesion  of  the  funiculus  to  the  whole  length  of  one  side  of  what 
would  otherwise  be  an  orthotropous  ovule.* 

568.  What  are  called  amphiiropous  or  heterotropous  ovules, 
which  are  straight,  with  the  chalaza  at  one  end,  the  micropyle  or 
apex  at  the  other,  and  the  hilum  half  way  between  the  two  (as  in 
Fig.  412),  arise  from  the  adhesion  of  the  funiculus  for  a  short  dis- 
tance only,  forming  a  raphe  of  only  half  the  length  of  the  ovule. 
As  the  free  funiculus  in  such  cases  generally  diverges  at  right  an- 
gles from  the  axis  of  the  ovule,  so  that  its  proper  base  and  apex 
become  lateral,  these  ovules  or  seeds  are  sometimes  termed  peltate^ 
or  transiierse. 

569.  Campylotropous  ovules  (Fig.  415)  differ  from  the  ortho- 
tropous in  being  curved  during  their  development,  so  that  the  ori- 
fice or  apex  is  brought  into  juxtaposition  with  the  base ;  which  in 
this  case  is  both  hilum  and  chalaza. 

570.  It  is  important  to  notice  the  situation  of  the  orifice,  or  fora- 
men, of  the  ovule,  as  it  indicates  the  future  position  of  the  radicle 
of  the  embryo  (631),  which  is  invariably  directed  towards  the  fo- 
ramen. Its  situation  with  respect  to  the  hilum  varies  in  the  differ- 
ent kinds  of  seeds  :  in  those  which  arise  from  orthotropous  ovules, 
it  points  in  the  direction  exactly  opposite  the  hilum  (Fig.  453) ;  in 
the  anatropous  form,  it  is  brought  close  to  the  hilum,  so  that  it  is 
ordinarily  said  to  point  to  it  (Fig.  454-456) ;  in  campylotropous 
seeds,  it  is  also  brought  round  to  the  hilum  ;  while  in  the  amphitro- 
pous,  it  points  in  a  direction  nearly  at  a  right  angle  with  the  hilum. 


*  Thus,  in  most  Cistacese,  the  ovules  are  orthotropous,  but  in  one  small  ge- 
nus (Fumana)  the  funiculus  usually  adheres  to  the  side  of  the  ovule,  and 
renders  it  anatropous.  On  the  contrary,  sometimes  anatropous  ovules  become 
orthotropous  in  the  seed,  by  the  separation  of  the  raphe  from  its  face. 


FERTILIZATION.  313 


Sect.  IX.     Fertilization. 


571.  Many  important  points  respecting  the  fertilization  of  the 
ovule  are  still  unsettled.  Our  restricted  limits  forbid  an  account 
of  the  various  more  or  less  conflicting  views  which  prevail,  or 
have  recently  prevailed.  The  principal  disputed  questions,  how- 
ever, now  relate  to  the  first  step  in  the  formation  of  the  embryo. 
The  action  of  the  pollen,  through  which  it  is  placed  in  connection 
with  the  nucleus  of  the  ovule,  is  now  satisfactorily  known. 

572.  The  arrangement  and  adjustment  of  parts,  mechanical  and 
otherwise,  which  secure  the  application  of  the  pollen  to  the  stig- 
ma, are  so  extremely  diversified  in  diflTerent  plants,  that  we  can- 
not undertake  to  give  even  a  general  account  of  them  here.  The 
adaptation  is  sometimes  in  the  relative  length  of  the  floral  organs  in 
connection  with  the  position  of  the  flower,  whether  erect,  inclined, 
or  nodding ;  sometimes  juxtaposition  is  effected  through  transient, 
and  often  sudden  movements,  whether  mechanical  (by  elasticity) 
or  spontaneous,  which  will  be  mentioned  in  another  place.  Fre- 
quently the  anthers  open  and  the  pollen  is  applied  to  the  stigma 
while  the  parts  are  still  approximated  in  the  bud.  In  moncecious 
plants  the  staminate  blossoms  are  commonly  situated  adjacent  to 
the  pistillate,  or  else  raised  above  them,  as  in  Indian  Corn.  In  dios- 
cious  plants,  as  indeed  in  a  vast  number  of  others,  much  is  left  to 
the  action  of  the  winds,  or  of  insects,  which  convey  the  pollen  from' 
one  blossom  to  another ;  and  the  immense  abundance  of  pollen, 
especially  in  monoecious  and  dioecious  plants,  greatly  diminishes  the 
chance  of  failure.  The  loose  papillae,  or  short  projecting  hairs  of 
the  stigma,  and  especially  the  viscous  fluid  which  at  this  time  al- 
ways moistens  its  surface,  serve  to  retain  the  grains  of  pollen  on 
the  stigma  when  they  have  once  reached  it.  The  following  brief 
statement  comprises  the  essential  substance  of  what  is  known  re- 
specting the  immediate 

573.  Action  of  the  Pollen.  The  grain  of  pollen  becomes  turgid^ 
as  it  absorbs  by  endosmosis  (37)  the  viscous  moisture  of  the  stig- 
ma :  its  inner  membrane  consequently  extends,  breaks  through  the 
scarcely  extensible  outer  coat  at  some  one  point  (or  occasionally 
at  two  or  three  points.  Fig.  419),  and  lengthens  into  a  delicate 
tube,  filled  with  the  liquid  and  molecular  matter  (fovillse,  535)  that 
the  grain  contains.  This  tube  (Fig.  416-419),  remaining  closed 
at  the  extremity,  penetrates  the  loose  tissue  of  the  stigma,  and  is 
27 


814 


FERTILIZATION. 


prolonged  downwards  into  the  style,  gliding  along  the  interspaces 
between  the  very  loosely  disposed  cells 
of  the  conducting  tissue,  where  it  finds 
abundant  moisture,  and  at  length  reaching 
the  placenta  or  some  other  part  of  the  in- 
terior of  the  ovary.  This  prolongation 
into  a  tube,  often  many  hundred  times  the 
diameter  of  the  pollen-grain,  is  a  true 
growth,  after  the  manner  of  elongating 
cells  (35,  97),  except  that  it  seldom  if 
ever  ramifies,  nourished  by  the  organ iza- 
ble  moisture  of  the  style  which  it  imbibes 
in  its  course.  Now  the  orifice  of  the 
ovules,  or  a  projection  of  the  nucleus  beyond  the  orifice,  is  at  this 
time  brought  into  contact  with,  or  proximity  to,  that  portion  of  the 
walls  of  the  ovary  from  which  the  pollen-tubes  emerge ;  and  a 
pollen-tube  thus  reaches  the  nucleus,  in  which  the  nascent  embryo 
subsequently  appears. 

574.  The  pollen-tubes  may  be  readily  inspected  under  the  mi- 
croscope in  many  plants ;  in  none  more  readily  than  in  the  Ascle- 
pias,  or  Milkweed,  one  of  the  plants  in  which  this  subject  was  so 
admirably  investigated  by  Mr.  Brown.  In  that  family,  the  pollen- 
grains  of  each  cell  of  the  anther  (Fig.  420)  cohere  in  a  mass ;  and 
these  pollen-masses,  dislodged  from  their  cells  (Fig.  421, 422),  usu- 
ally bj  the  agency  of  insects,  and  brought  into  proximity  with  the 
base  of  the  stigma,  protrude  their  tubes  in  great  abundance,  and 
of  a  size  which  renders  them  Yisible  with  a  very  moderate  magni- 
fying power.  They  may  readily  be  seen  to  penetrate  the  base  of 
the  stigma,  as  in  Fig.  423,  and  separate  grains  with  their  tubea 
may  be  detached  liom  the  mass  (Fig.  425,  426);  but  to  trace 
tfior  oomse  down  the  style  (as  in  Fig.  424),  and  to  their  final  de»- 
tBBBtion,  requires  much  tact  in  manipulation  and  the  best  means  of 
icseaich. 

575l  F«HaliM  tf  ttc  JUtajV.  Before  the  poUen-tube  reaches 
^he  ofnde,  die  nudeas  of  die  btto-  eadnbito  a  carily  in  its  interior, 
towards  the  ^er.   In  the  Mistlfftne,  this  caYity  would  seem  to  be  a 


FORMATION  OF  THE  ENBRTO. 


315 


mere  hollowing  out,  produced  by  absorption,  and  having  no  evident 
lining  membrane. 
Usually,  however, 
in  this  cavity  filled 
with  fluid, —  or  de- 
veloped with  it  so 
as  to  form  its  spe- 
cial parietes,  —  a 
large  cell  appears 
and  expands  into 
a  bladder  or  clos- 
ed sac  of  consid- 
erable size.  This 
is  the  sac  of  the 
ajnnios     of     Mr.  __ 

Brown,    the    cm- 

hryo-sac  {sac  emhryonaire)  of  the  French  botanists.*     In  this  sac 
the  embryo  is  formed. 

576.  From  Linnaeus  downwards,  until  recently,  it  was  univer- 
sally supposed  that  the  embrj^o  originated  in  the  ovule,  which  was 
in  some  way  or  other  fertilized  by  the  pollen.  Since  the  discovery 
of  the  pollen-tube  in  1824  by  Amici,  and  its  actual  penetration  to 
the  nucleus  of  the  ovule  by  Mr.  Brown,  however,  the  late  Professor 
Horkel,  and  his  nephew,  Schleiden,  —  who  traced  it  quite  to  the 
embryo-sac,  —  have  propounded  a  very  different  view.  Schleiden 
and  his  followers  strongly  maintain,  as  the  result  of  direct  observa- 
tion, that  the  apex  of  the  pollen-tube  itself  becomes  the  embryo ; 


*  **  The  OTule  ia  produced  by  the  development  of  one  cell  of  the  pUeenta 
into  a  cellular  body,  which  essentially  consists  of  a  central  row  of  cells,  in- 
closed by  a  variable  number  of  layers  of  cells.  One  of  ihe  cells  of  the  central 
row  enlarges  and  displaces  a  varying  quantity  of  the  rest  of  the  tissue  of  the 
ovule.  This  is  the  embryo-sac"  Hoflmeister,  as  rendered  by  Henfrey,  Bot. 
GaxeUt^  I.  p.  127. 


FIG.  430.  A  back  rlew  of  a  •tainen  of  the  common  MiUni«ed  (AadepiasD,  tlM 
cut  away.  421.  A  suroen  more  magnified,  with  the  two  polkit-maaaas  eelMCtes  bj  their 
eaudieles,  each  to  a  ^nd  from  the  Mmnait  of  the  etlgiBMte  boAf,  to  wM^  a  poMan  nwi  tnm 
an  aJjaceni  am  her  is  already  adheraaU    Itt.  A  pair  of  delacheil  pcJaa-aiiMM  (each  from  a 

tlitTereai  aiithfr)  suspendMl  by  their  eaudieles  fron  the  {laad.  4S3.  Someef  the  poliea  maeeee, 
wilh  their  tubea  penetrating  the  atisrnw  (aAer  Brown).  4SiL  A  eectioo  thnmell  the  Yargt  «.ig- 
malic  ttodr  and  a  part  of  the  summit  of  one  of  the  atylea,  ahewta^  the  oooree  of  the  poHeo- 
tubej.    425,  426.  Pollangraina  wilh  their  tul>es,  highly  mafatted.    (The  atnKlwa  of  Ihaaa 

^lingular  flowers  will  t«  more  fully  explained  under  the  ordw  Awl^tdmnm,} 


316  FERTILIZATION. 

that  on  reaching  the  embryo-sac  it  indents  the  latter,  pushing  it 
forwards  so  as  to  reverse  a  portion  on  itself,  in  which  cavity  the 
apex  of  the  pollen-tube  swells  into  an  oval  or  globular  form,  and  its 
contents  are  transformed  into  new  cells,  which,  as  they  grow  and 
multiply,  shape  themselves  into  the  embryo.  Or,  according  to  other 
observations,  it  is  maintained  that  the  apex  of  the  pollen-tube  pierces 
the  embryo-sac  and  developes  into  the  embryo  in  its  interior,  in 
the  manner  last  stated.  It  is  now  unnecessary  to  adduce  the  de- 
tails of  the  researches,  or  the  theoretical  considerations,  by  which 
this  hypothesis  was  supported.  For,  besides  the  researches  of  Mir- 
bel,  in  1839,  the  investigations  made,  between  the  year  1846  and 
the  present  time,  by  Amici,  Mohl,  K.  MuUer,  linger  (who  had 
maintained  the  hypothesis  in  question),  Hoffmeister,  Henfrey,  and 
Tulasne,  have  completely  overthrown  the  foundations  on  which  it 
rested  ;  by  proving, —  1st.  That  the  embryonal  vesicle^  from  which 
the  embryo  is  developed,  exists  in  the  embryo-sac,  in  some  cases 
at  least,  before  the  pollen-tube  has  reached  the  ovule  ;  so  that  it 
cannot  owe  its  origin  to  the  pollen-tube,  directly  or  indirectly,  and 
still  less  can  it  be  a  prolongation  of  it.  2d.  That  end  of  the  pol- 
len-tube is,  for  the  most  part',  at  least,  applied  to  the  exterior  of  the 
embryo-sac  at  a  point  distinguishably,  and  often  considerably,  dis- 
tant from  that  where  the  embryo  is  developed  within.* 

577.  The  general  results  which  all  these  recent  investigations 
conspire  to  establish  are  these: — The  pollen-tube  entering  the 
orifice  of  the  ovule,  penetrates  the  tissue  of  the  nucleus  until  it 
reaches  the  summit  of  the  embryo-sac.  Sometimes  its  extremity 
slightly  indents  it ;  often  it  glides  downwards  along  the  surface  of 
the  sac  for  a  little  distance  ;  in  either  case  it  barely  adheres  to  the 

*  The  latest  memoir  on  this  subject,  that  of  Tulasne  (in  Ann.  Sci.  Kat  for 
July  and  August,  1849),  is  remarkable  not  only  for  its  thoroughness  and  its 
admirable  illustrations,  but  because  the  author  here  points  out  and  corrects 
the  error  into  which  he  had  formerly  fallen,  which  led  him  to  conclude  that 
the  end  of  the  pollen-tube  actually  penetrates  the  embryo-sac,  and  gives  rise 
to  the  embryonal  vesicle.  —  Hoifmeister  asserts  (as  rendered  by  Henfrey), 
that  although  the  pollen-tube  generally  rests  upon  the  outside  of  the  embryo- 
sac,  yet  in  a  very  few  isolated  cases  it  perforates  it;  but  "even  when  the 
pollen-tube  thus  penetrates  into  the  interior  of  the  embryo-sac,  its  end  remains 
perfectly  closed,  and  the  membrane  of  the  germinal  vesicle  quite  uninjured  : 
in  no  case  can  a  direct  passage  of  the  contents  of  one  into  the  other  take  place. 
The  impregnation  is  the  result  solely  of  an  endosmotic  exchange  of  the  fluid 
contents."     Henfrey,  Bot.  Gazette,  I.  c. 


FORMATION  OF  THE  EMBRYO.  317 

membrane,  makes  no  further  growth,  and  after  a  time  begins  to 
'  wither  away.  It  may  here  be  remarked  that  the  pollen-tube  with- 
ers or  decays  from  above  downwards;  when  its  course  is  long, 
the  end  in  connection  with  the  pollen-grain  commonly  withers 
while  the  other  end  is  still  growing  onwards  towards  the  ovule. 
Within  the  embryo-sac  near  or  at  its  apex  (or  micropylar  end), 
and,  in  some  cases  at  least,  before  the  pollen-tube  enters  the  ovule, 
a  small  cell  makes  its  appearance  ;  this  is  the  embryonal  vesicle  or 
germinal  vesicle.  This  cell  is  either  developed  in  contact  with  the 
membrane  of  the  embryo-sac,  or  it  soon  adheres  to  it  by  one  end, 
very  near  but  not  always  exactly  opposite  the  point  to  which  the 
apex  of  the  pollen-tube  is  applied  without.  This  cell  is  the  proper 
germ  or  rudiment  of  the  embryo.  It  is  fertilized,  apparently,  by 
the  imbibition  of  the  fluid  of  the  pollen  by  endosmosis  through  the 
intervening  membranes,  namely,  that  of  the  pollen-tube,  that  of 
the  embryo-sac,  and  that  of  the  embryonal  vesicle  itself;  the  vital- 
ly active  contents  of  two  cells  of  different  origin  being  thus  com- 
mingled, as  in  the  simpler  process  of  conjugation  in  the  lower  Cryp- 
togamous  plants  (102).  Thus  endued  with  new  force,  the  embry- 
onal vesicle,  which  would  otherwise  soon  wither  away,  at  once 
commences  an  active  development ;  it  elongates  downwards,  or 
from  its  free  extremity  ;  minute  granular  matter  appears  in  the 
interior,  which  was  before  perfectly  clear  and  transparent ;  soon  a 
few  transverse  partitions  are  seen,  and  it  is  thus  converted  into  a 
chain  of  cells,  each  of  which  contains  a  distinct  nucleus.  This 
body,  which  may  attain  considerable  elongation,  by  the  continued 
elongating  growth  and  division  of  the  terminal  cell  (32-34),  be- 
comes the  Suspensor.  The  lowest  of  its  cells  retains  a  globular 
shape,  and  enlarges  ;  its  contents  become  turbid,  and  are  converted 
into  a  mass  of  delicate  cells,  either  by  original  cell-formation  in 
the  interior  (28),  or  by  cell-division  (31,  if  there  be  indeed  any 
real  difference  in  the  two  modes),  as  before,  only  that  here  the  di- 
vision takes  place  in  every  direction.  This  globular  body,  hung 
on  the  extremity  of  the  suspensor,  is  the  Embryo  (Fig.  430). 
As  it  grows  it  soon  begins  to  assume  its  proper  form.  In  a 
Dicotyledonous  plant,  as  is  rudely  shown  in  the  annexed  figures, 
the  end  farthest  from  the  suspensor  begins  to  be  two-lobed  (Fig. 
432) ;  the  lobes  increase  by  ordinary  cellular  growth,  and  form 
the  Cotyledons  (Fig.  433,  434)  ;  the  opposite  extremity  is  of 
course  the  Radicle.  The  suspensor  usually  disappears  before  the 
27* 


318 


FERTILIZATION. 


embryo  has  attained  its  full  development.     A  monocotyledonous 
embryo  has  this  end  undivided.     In  the  polycotyledonous  embryo 


of  Pines,  &c.,  the  budding  apex  divides  successively  as  it  grows 
into  four,  six,  or  more  lobes,  each  of  which  becomes  a  cotyledon.* 

*  The  principal  points  of  discordance  in  the  later  investigations  are  con- 
nected with  the  embryonal  vesicle.  According  to  Mohl,  Henfrey,  &c.,  in 
Orchis  Morio,  as  many  as  three  germinal  vesicles  exist  within  the  apex  of  the 
embryo-sac,  anterior  to  fertilization,  as  minute  free  cells,  formed  from  so  many 
nuclei;  one  (or  sometimes  more  than  one)  of  them  enlarges  soon  after  the  pol- 
len-tube has  reached  the  embryo-sac,  and  developes  in  the  manner  above  de- 
scribed. According  to  Hoffmeister,  also,  in  CEnothera,  two  or  three  germinal 
vesicles  appear  a  long  time  before  fertilization,  from  free  cell-nuclei,  forming  so 
many  delicate,  free  cells,  one  of  which  being  fertilized  developes  into  the 
embryo  in  the  manner  already  described,  while  the  others  perish.  The  results 
of  the  more  recent  researches  of  Tulasne  (upon  the  embryogeny  of  Scrophu- 
lariacea3,  Campanulaceje,  and  Cruciferje)  principally  differ  in  this;  —  that  he 
was  unable  to  detect  any  embryonal  vesicle  before  the  pollen-tube  had  pene- 
trated to  the  embryo-sac  ;  and  afterwards  he  finds  only  one,  mostly  of  an  elon- 
gated form,  and  always  from  the  first  attached  by  one  end  to  the  inside  of  the 
wall  of  the  embryo-sac,  at  a  point  near  that  to  which  the  pollen-tube  is  applied 
externally.     He  is  led  to  conclude  that  the  embryonal  vesicle  originates  at 


FIG.  427.  Plan  of  a  vertical  section  of  the  pistil  of  a  Polygonum,  and  of  the  erect  orthotro- 
pous  ovule  it  contains,  at  the  period  of  fertilization :  the  grains  of  pollen  resting  on  the  stigma 
have  sent  their  tubes  down  the  style  to  the  mouth  of  the  ovule :  and  the  nascent  embryo-sac  is 
seen  at  the  apex  of  the  nucleus.  428.  A  pollen-grain  detached,  with  its  tube.  429.  Plan  of  the 
vertical  section  of  the  ovule  more  magnified,  andat  a  later  period :  the  nascent  embryo  with  its 
suspensor  seen  in  the  embryo-sac.  430.  The  nascent  embryo  with  its  suspensor,  more  magni- 
fied. 431-433.  Views  of  the  successive  development  of  the  embryo.  434.  The  embryo  as  it 
exists  in  the  seed. 


FORMATION  OF  THE  EMBRYO.  319 

578.  Two  or  more  embryos  are  frequently  found  in  the  same 
seed,  in  the  Orange,  the  Onion,  and  many  other  cases.  There 
are  generally  two  embryos  in  the  seed  of  the  Mistletoe ;  and  there 
is  constantly  a  plurality  of  embryos  in  Pines  and  other  Gymno- 
spermous  plants  (560),  though  all  but  one  are  more  commonly 
abortive  or  rudimentary.* 

579.  Contemporaneous  with  the  production  of  the  embryo,  a 
cell-formation  takes  place  in  the  mucilaginous  liquid  contained  in 
the  embryo-sac,  soon  filling  the  space  with  an  exceedingly  soft  and 
delicate  parenchyma,  proceeding  from  the  wall  of  the  sac  inwards. 
Sometimes  the  enlarging  embryo,  as  it  grows,  obliterates  this  deli- 
cate, half-fluid  tissue,  is  nourished  by  its  contents,  and  at  maturity 
fills  the  integuments  of  the  seed  completely.  In  other  cases,  the 
growth  of  the  embryo  in  the  seed  is  arrested  before  it  fills  the  em- 
bryo-sac :  then  this  new  tissue  that  surrounds  it,  solidified  by  inter- 
nal deposition,  or  with  its  cells  filled  with  starch,  &c.,  becomes 
permanent,  and  forms  the  albumen  of  the  seed  (627) ;  or  some- 
times this  cellular  growth  and  deposit  of  nutritive  matter  take 
place  in  the  persistent  body  of  the  nucleus  of  the  ovule,  external 
to  the  embryo-sac,  as  in  Nymphsea. 

580.  With  the  development  of  the  embryo,  the  ovule  becomes 
the  seed.     Its  further  history  should  follow  that  of  the  fruit. 

this  point,  either  from  a  sort  of"  dedoublement "  of  the  raerabrane  of  the  era- 
bryo-sac,  or  from  a  nucleus  adherent  there ;  and  he  inclines  to  think  that  its 
formation  does  not  precede  the  conjunction  of  the  pollen-tube  with  the  em- 
bryo-sac, but  that  it  is  the  first  visible  result  of  this  union.  And,  calling  to 
mind  that  linger  met  with  free  cells  in  the  unimpregnated  embryo-sac  of 
Hippuris  vulgaris,  formed  from  free  and  floating  nuclei,  but  which  were  al- 
ways resolved  before  the  appearance  of  the  real  embryonal  vesicle,  he  sug- 
gests that  the  free  cells  seen  by  HoflTmeister  may  be  of  the  same  kind.  M. 
Tulasne  plausibly  considers  that  the  embryo-sac  is  the  cell  which  receives 
the  fluid  of  the  pollen,  and  that  in  its  cavity,  therefore,  the  contents  of  two 
cells  are  commingled ;  the  result  of  which  union  gives  rise  to  the  embryonal 
vesicle,  or  potential  embryo,  endowed  from  the  first  with  the  new  specific 
force  which  it  manifests  in  its  ulterior  development.  We  can  only  refer  the 
inquirer  to  this  original  memoir;  an  abstract  can  hardly  be  made  intelligible 
to  the  uninstructed  reader,  without  the  plates. 

*  In  Coniferae  (at  least  in  the  Pines)  the  embryo  is  not  developed  from  the 
embryonal  vesicle  until  long  after  the  cavity  of  the  embryo-sac  is  filled  with 
the  cellular  tissue  that  forms  the  albumen  of  the  seed ;  and  its  formation  ap- 
pears to  be  in  other  respects  peculiar. 


320 


THE    FRUIT. 


CHAPTER    X. 

OF    THE    FRUIT. 

Sect.  I.     Its  Structure,  Transformations,  and  Dehiscence. 

581.  The  fertilized  ovary  soon  begins  to  increase  in  size,  and 
commonly  to  undergo  some  change  in  texture ;  either  becom- 
ing dry  and  membranaceous,  crustaceous,  or  even  woody,  or  else 
by  an  opposite  change  becoming  fleshy,  pulpy,  or  juicy  :  it  is  now 
called 

582.  The  Pericarp,  or  Seed-vessel.  The  pericarp  and  the  seeds  it 
incloses  together  constitute  the  Fruit  ;  a  term  which  has  a  more 
extensive  signification  in  botanical  than  in  ordinary  language  ;  be- 
ing applied  to  all  mature  pistils,  of  whatever  form,  size,  or  texture. 
The  fruit  likewise  comprises  whatever  organs  may  be  adnate  to 
the  pistils  (465).  Such  incorporated  parts,  like  the  fleshy  calyx  of 
the  Apple  and  Quince  (Ord.  Rosaceae),  sometimes  make  up  the 
principal  bulk  of  the  fruit. 

583.  It  may  be  remarked  that  a  similar  accumulation  of  fleshy 
or  pulpy  matter  may  take  place  in  adjacent  organs  wholly  uncon- 
nected with  the  pistil ;  as  in  the  free  calyx  of  the  Strawberry  Blite 
(Fig.  993,  995),  which  becomes  greatly  thickened,  red,  and  jui- 
cy;  and  in  .the  Wintergreen  (Fig.  795  -  797),  where  the  calyx, 
at  first  small  and  membranaceous,  and  entirely  free  from  the 
ovary,  gradually  enlarges  after  flowering,  and  is  transformed  into 
a  red,  pulpy  berry,  surrounding  the  true  fruit,  which  is  a  small 
and  dry  pod.  The  pulp  of  the  strawberry,  moreover,  is  no  part  of 
the  proper  fruit ;  but  consists  of  the  enlarged  and  juicy  receptacle, 
or  apex  of  the  flower-stalk,  bearing  the  numerous  small  and  dry 
grains,  or  true  fruits,  upon  its  surface.  The  bread-fruit  and  the 
pine-apple  are  still  more  complex,  being  composed  of  a  whole 
head  or  spike  of  flowers,  with  their  bracts  and  common  receptacle 
all  consolidated  into  a  single  fleshy  mass.  The  mulberry  is  a  mul- 
tiple fruit  of  the  same  kind  (Fig.  244),  in  which  the  component 
parts  may  readily  be  identified.  The  structure  of  the  fig,  which 
may  be  likened  to  a  mulberry  or  a  bread-fruit  turned  inside  out, 
has  already  been  explained  (395,  Fig.  241-243). 

584.  Under  the  general  name  of  fruit,  therefore,  even  as  the 


ITS  STRUCTURE  AND  TRANSFORMATIONS.         321 

word  is  used  by  the  botanist,  things  of  very  different  structure  or 
of  different  degrees  of  complexity  are  confounded.  These  need  to 
be  properly  distinguished.  For  the  present,  we  will  consider  the 
fruit  in  the  stricter  sense,  as  consisting  of  the  matured  pistil  alone, 
whether  simple  or  compound,  either  free  or  in  combination  with 
any  floral  organs,  such  especially  as  the  tube  of  the  calyx,  which, 
being  adnate  to  the  ovary  in  the  flower,  is  necessarily  incorpo- 
rated with  the  pericarp  in  fructification. 

585.  The  pericarp,  being  merely  the  matured  pistil,  should  ac- 
cord in  structure  with  the  latter,  and  contain  no  organs  or  parts 
that  do  not  exist  in  the  fertilized  ovary.  Some  alterations,  how- 
ever, often  take  place  during  the  growth  of  the  fruit,  in  conse- 
quence of  the  abortion  or  obliteration  of  parts.  Thus,  the  ovary  of 
the  Oak  (Fig.  1044)  consist^  of  three  cells,  with  a  pair  of  ovules  in 
each  ;  but  the  acorn,  or  ripened  fruit,  presents  a  single  cell,  filled 
with  a  solitary  seed.  In  this  case,  only  one  ovule  is  matured,  and 
two  cells  and  five  ovules  are  suppressed.  The  ovary  of  the  Horse- 
chestnut  and  Buckeye  is  similar  in  structure  (Fig.  659-661),  and 
seldom  ripens  more  than  one  or  two  seeds  :  but  the  abortive  seeds 
and  cells  may  be  detected  in  the  ripe  fruit.  The  ovary  of  the 
Birch  (Fig.  1053)  is  two-celled,  with  a  single  ovule  in  each  cell : 
the  fruit  is  one-celled,  with  a  solitary  seed  ;  one  of  the  ovules  or 
young  seeds  being  uniformly  abortive,  while  the  other  in  enlarging 
pushes  the  dissepiment  to  one  side,  so  as  gradually  to  close  the 
empty  cell  (as  in  Fig.  1056).  The  Elm  presents  a  similar  case 
(Fig.  1013,  1014) ;  and  such  instances  of  suppression  in  the  fruit 
of  parts  actually  extant  in  the  ovary  are  not  uncommon. 

586.  On  the  other  hand,  the  fruit  sometimes  exhibits  more  cells 
than  the  pistil ;  as  in  the  two-celled  ovary  of  Datura  Stramonium, 
which  soon  becomes  spuriously  four-celled  by  the  projection  of  the 
placentae  on  each  side,  so  as  to  reach  and  cohere  with  a  projection 
of  the  dorsal  suture  on  each  side.  So,  also,  many  legumes  are 
divided  transversely  into  several  cells,  although  the  ovary  was  one- 
celled  with  a  continuous  cavity  in  the  flower. 

587.  Ripening.  The  growing  fruit  attracts  its  food  from  sur- 
rounding parts  in  the  same  manner  as  leaves.  When  the  pericarp 
preserves  its  green  color  and  leaf-like  texture  (as  in  the  Pea,  &c.), 
it  is  furnished  with  stomates,  and  acts  upon  the  air  like  ordinary 
leaves.  Those  which  become  fleshy  or  juicy  acquire  that  condi- 
tion by  the  accumulation  of  elaborated  sap  in  their  tissue ;  where 


323  THE    FRUIT. 

it  undergoes  various  transformations,  analogous  to  those  which  take 
place  in  other  parts  of  the  plant. 

588.  Most  pulpy  fruits  are  tasteless  or  slightly  bitter  during  their 
early  growth  ;  at  which  period  their  structure  and  chemical  com- 
position is  similar  to  that  of  leaves,  consisting  of  cellular  with  some 
woody  tissue  ;  and  their  action  upon  the  atmosphere  is  likewise  the 
same  (346).  In  their  second  stage,  they  become  sour,  from  the 
production  of  acids  (353),  such  as  tartaric  acid  in  the  grape ;  the 
citric  in  the  lemon,  orange,  and  the  cranberry ;  the  malic  in  the 
apple,  gooseberry,  &c.  At  this  period  they  exhale  very  little  ox- 
ygen, or  even  absorb  that  substance  from  the  surrounding  air. 
The  acid  increases  until  the  fruit  begins  to  ripen,  when  it  gradu- 
ally diminishes,  and  sugar  is  formed.  In  the  third  stage,  or  that  of 
ripening,  the  acids,  as  well  as  the  fibrous  and  cellular  tissues,  grad- 
ually diminish  as  the  quantity  of  sugar  increases ;  the  latter  be- 
ing produced  partly  at  the  expense  of  the  former,  by  transforma- 
tions which  are  very  intelligible  to  the  chemist,  and  which  he  can 
partially  imitate.  A  chemical  change,  similar  to  that  of  ripening, 
takes  place  when  the  green  fruits  are  cooked  ;  the  acid  and  the 
mucilaginous  or  other  products,  by  the  aid  of  heat  reacting  upon 
each  other,  are  both  converted  into  sugar.  Mingled  with  the  sac- 
charine matter,  a  large  quantity  of  vegetable  jelly  (83)  is  also 
produced  in  most  acidulated  pulpy  fruits,  existing  in  the  form  of 
pectine  and  pectic  acid.  These  arise  from  the  reaction  of  the 
vegetable  acids  during  ripening  upon  the  dextrine  and  other  assim- 
ilated neutral  products  accumulated  in  the  fruit. 

589.  Frequently  different  parts  of  the  thickness  of  the  pericarp 
undergo  dissimilar  changes  during  fructification  and  ripening  ;  the 
inner  portion  hardening  while  the  exterior  becomes  fleshy,  or  vice 
versa.  When  the  walls  of  a  pericarp  are  thus  distinguished  into 
two  separable  portions,  the  exterior  receives  the  name  of  Epicarp, 
or  ExocARP,  and  the  interior  that  of  Endocarp.  When  the  exte- 
rior part  is  fleshy  or  pulpy,  as  in  the  peach  (Fig.  447)  and  plum, 
it  is  termed  the  Sarcocarp  ;  and  the  hard  shell  or  endocarp  which 
contains  the  seed  is  called  the  Ptjtamen. 

590.  Often  the  walls  of  the  pericarp  preserve  a  nearly  uniform 
texture  throughout,  becoming  either  entirely  membranaceous,  as  in 
many  capsules  or  pods ;  or  fleshy,  as  in  the  berry ;  or  indurated 
throughout,  as  in  the  acorn. 

591.  A  part,  and   in  membranaceous  or  other  dry  fruits  the 


ITS    DEHISCENCE.  323 

whole,  of  the  nutritive  matter  collected  in  the  pericarp  is  absorbed 
by  the  placenta  (543)  and  conveyed  to  the  seed ;  where  the  por- 
tion which  is  not  consumed  in  its  growth  is  stored  up,  either  in  the 
embryo  or  around  it,  as  a  provision  for  its  future  development  in 
germination. 

592.  Certain  fruits  remain  closed  and  entire  at  maturity,  as  the 
acorn,  apple,  grape,  &c.  ;  when  they  are  said  to  be  indehiscent. 
Others  separate  (wholly  or  partially)  into  several  pieces,  and  dis- 
charge the  seeds ;  sometimes  bursting  irregularly,  but  commonly 
opening  in  a  uniform  and  regular  manner  for  each  species  ;  these 
are  said  to  be  dehiscent. 

593.  Dehiscence,  when  regular  and  normal,  takes  place  in  a  ver- 
tical direction,  by  the  opening  of  one  or  both  sutures  (541),  or  by 
the  disjunction  of  confluent  parts  (546).  The  pieces  into  which  a 
dehiscent  pericarp  separates  are  called  its  valves. 

594.  A  simple  carpel  dehisces  either  by  the  opening  of  the  ven- 
tral suture,  as  in  the  Columbine,  the  Peony,  &c. ;  or  by  the  dor- 
sal suture  also,  as  in  the  Pea  and  Bean. 

595.  The  dehiscence  of  a  pod  which  results  from  the  union  of 
two  or  more  carpels  may  take  place  by  the  separation  of  the  con- 
stituent carpels  from  each  other,  and  by  the  opening  of  the  ventral 
sutures,  as  in  the  Colchicum  (Fig.  1115),  Rhododendron  (Fig.  793), 
and  in  the  diagram  (Fig.  435).  In  this  case,  the  pericarp  splits 
through  the  dissepiments  ;  whence  the  dehiscence  is  said  to  be  sep- 
ticidal.  Sometimes  the  carpels,  although  separating  from  each 
other  in  this  manner,  remain  closed  or  indehiscent,  as  in  the  Mad- 
der (Fig.  748),  the  Vervain  (Fig.  869),  &c. :  the  separable  car- 
pels are  often  termed  cocci ;  and  the  fruit  is  said  to  be  dicoccous, 
tricoccous^  &c.,  according  to  their  number. 


437 

596.  Otherwise,  the  dehiscence  may  take  place  by  the   dorsal 

FIG.  435  -437.    Diagrams  of  the  dehiscence  of  capsules  (horizontal  sections) :  435,  the  sep' 
ticidal ;  436,  the  loculicidal ;  437,  the  seplifragal. 


324 


THE    FRUIT. 


suture  of  each  component  carpel  opening  directly  into  the  back  of 
the  cells,  when  the  pericarp  is  more  than  one-celled;  whence  this 
dehiscence  is  said  to  be  loculicidal  (as  in  Fig.  621,  908,  919,  and 
the  diagram,  Fig.  436).  In  such  cases  the  dissepiments  remain 
attached  to  the  middle  of, each  valve.  In  the  Helianthemum 
(Fig.  549),  and  many  other  plants,  we  have  an  example  of  locu- 
licidal dehiscence  in  a  one- celled  pericarp  with  parietal  placentae  ; 
which  in  this  case  are  borne  directly  on  the  middle  of  each  valve. 
On  the  other  hand,  septicidal  dehiscence  in  a  similar  pericarp  is 
at  once  recognizable  by  the  placentse  occupying  the  margins  of 
the  valves. 

597.  Sometimes  the  placentae,  being  firmly  coherent  with  each 
other,  break  away  from  the  dissepiments  and  remain  united  in  the 
axis,  forming  a  column,  or  columella,  as  in  Rhododendron  (Fig. 
793),  Polemonium,  and  Collomia  (Fig.  908),  &c. 

598.  Occasionally  the  dissepiments  remain  coherent  with  the 
axis  while  the  valves  separate  from  them,  as  in  the  Morning  Glory 
(Fig.  924),  and  in  the  diagram.  Fig.  437.  This  modification  is 
termed  septifragal  dehiscence.  In  like  manner,  parietal  placentae 
occasionally  separate  from  the  valves,  forming  what  has  been 
termed  a  replum;  as  in  Cruciferous  plants,  and  in  the  Poppy  Fam- 
ily. The  same  name  is  applied  to  the  persistent  border  of  the 
simple  pod  of  Mimosa  (Fig.  441). 

599.  Instead  of  splitting  into  separate  pieces,  the  sutures  of  the 
pericarp  sometimes  open  for  a  short  distance  at  their  apex  only,  as 
in  some  Chickweeds,  and  in  Tobacco  (Fig.  936),  and  the  Primrose 
(Fig.  826) ;  or  by  mere  points  or  pores,  as  in  the  Poppy. 

600.  In  a  few  cases  the  opening  takes  place  by  a  transverse 
line  passing  round  the  pericarp  across  the  sutures,  so  that  the  up- 
per part  falls  off  like  a  lid ;  as  in  Anagallis  (Fig.  830),  the  Plan- 
tain (Fig.  833),  the  Henbane  (941),  and  the  Purslane  (Fig.  568). 
In  Jeflfersonia,  the  opening  extends  only  half  way  round  the  peri- 
carp, and  the  lid  remains  attached  by  the  other  side,  as  by  a  hinge. 
This  anomalous  dehiscence  is  termed  circumcissile  or  transverse. 

Sect.  II.     The  Kinds  of  Fruit. 

601.  The  various  kinds  of  fruits  have  been  minutely  classified 
and  named ;  but  the  terms  in  ordinary  use  are  not  very  numerous. 
A  rigorously  exact  and  particular  classification,  discriminating  be- 


ITS    KINDS. 


325 


tween  the  fruits  derived  from  simple  and  from  compound  pistils,  or 
between  those  with  and  without  an  adnate  calyx,  becomes  too  re- 
condite and  technical  for  ordinary  use  in  descriptive  botany.  Tak- 
ing first  the  SIMPLE  fruits,  namely,  those  that  result  from  single 
and  separate  flowers,  the  principal  sorts  may  be  briefly  indicated 
as  follows. 

602.  A  Follicle  is  a  fruit  formed  of  a  single  carpel,  dehiscing  by 
the  ventral  suture  (541) ;  as  in  the  Larkspur  and  Columbine,  and 
the  Milkweed. 

603.  A  Legume,  or  Simple  Pod,  is  a  fruit  formed  of  a  single  car- 
pel, and  dehiscent  by  both  the  ventral  and  dorsal  sutures,  so  as  to 
separate  into  two  valves ;  as  in  the  Bean  and  Pea.  The  name  is 
extended  to  the  fruit  of  all  Leguminous  plants  (Ord.  Leguminosse), 
whatever  be  their  form,  and  whether  dehiscent  or  not.  A  legume, 
divided  into  two  or  more  one-seeded  joints,  and  falling  to  pieces  at 
maturity,  is  called  a  Loment,  or  lomentaceous  legume.  Some  of 
the  various  kinds  of  legume  are  shown  in  the  annexed  figures. 


604.  A  Drupe,  or  Stone-Fruil,  is  a  one-celled,  one  or  two-seeded 
simple  fruit  which  is  not  dehiscent,  with  the  inner  part  of  the  peri- 
carp {endocarp,  or  stone)  hard  or  bony,  while  the  outer  {exocarp,  or 
sarcocarp)  is  fleshy  or  pulpy.  It  is  the  latter  which  in  our  fruits 
so  readily  takes  an  increased  development  in  cultivation.      The 


fig.  433.  Open  legume  of  the  Pea:  a,  section  of  the  ovary.  439.  Embryo,  with  cotyle- 
dons laid  open.  440.  Loment  of  Desmodium.  441.  Loment  of  Mimosa:  b,  one  of  its  dehis- 
cent joints  which  has  fallen  away  from  the  persisting  border  or  frame  (replum),  seen  in  442. 
443.  The  jointed  indehiscent  legume  of  Sophora.  444.  A  legume  of  Astragalus,  cut  across  near 
the  summit  to  show  how  it  becomes  partly  or  entirely  two-celled  by  the  introflexion  of  the 
dorsal  suture.  445.  Similar  view  of  a  legume  of  Phaca,  where  the  ventral  suture  is  somewhat 
inlroflexed,    446.  A  legume  of  Medicago  lupulina,  spirally  coiled  into  a  globular  figure. 

28 


326 


THE    FRUIT. 


name  is  strictly  applicable  only  to  fruits  of  this  kind  produced  by 

the  ripening  of  a  single  car- 
pel ;  as  the  plum,  apricot, 
peach  (Fig.  447),  &c. ;  but 
is  extended  in  a  general  way 
to  all  one-celled  and  one  or 
two-seeded  fruits  of  similar 
texture  resulting  from  a  com- 
pound ovary,  and  even  to 
those  of  several  bony  cells  in- 
closed in  pulp,  as  in  the  Dogwood  (Fig.  240,  b).  The  latter,  how- 
ever, are  more  strictly  said  to  be  drupaceous,  or  drupe-like  fruits. 

605.  An  Achenium  is  a  small  and  dry  indehiscent  one-seeded 
pericarp,  formed  of  a  single  carpel ;  as  in  the  Buttercup,  and  the 
allied  genera  Anemone  and  Clematis,  where  they  are  often  termi- 
nated by  the  persistent  and  often  plumose  style,  in  the  form  of  a 
long  tail.  In  the  Rose  (Fig.  684,)  the  achenia  are  borne  on  the 
hollow  expansion  of  the  receptacle  which  lines  the  fleshy  tube  of 
the  calyx :  in  Calycanthus  the  achenia  (Fig.  693)  are  similarly 
inclosed  in  a  sort  of  false  pod  (Fig.  691,  695)  of  the  same  nature 
as  the  rose-hip,  while  in  the  Strawberry  (Fig.  678,  679),  they  are 
scattered  on  the  surface  of  the  enlarged  and  pulpy  receptacle ; 
where,  as  in  many  other  cases,  they  are  commonly  mistaken  for 
seeds.  But  they  are  all  furnished  with  styles,  which  show  their 
nature ;  and  on  cutting  them  across  we  observe  the  real  seed  loose 
in  the  cell.  These  seed-like  fruits  were  incorrectly  called  naked 
seeds  by  the  earlier  botanists.  The  strawberry,  raspberry^  &c., 
therefore,  taken  as  a  whole,  are  not  simple,  but  aggregate  fruits. 
In  the  Raspberry  and  Blackberry  (Fig.  680),  the  achenia  are 
changed  into  little  drupes  (604).  The  name  of  achenia  is  also 
applied  to  similar  one-seeded  fruits  resulting  from  a  one-celled 
ovary,  even  when  formed  of  more  than  one  carpel,  and  invested  by 
the  calyx-tube  ;  as  that  of  the  Sunflower  and  all  Composite  or 
Syngenesious  plants,  where  the  limb  of  the  calyx,  assuming  a  va- 
riety of  unusual  forms,  is  termed  the  Pappus  (Fig.  776). 

606.  A  Cremocarp  consists  of  a  pair  of  achenia  placed  face  to 
face,  and  invested  by  the  calyx-tube  ;    which,  when  ripe,  sepa- 


FIG.  447.  Vertical  section  of  a  peach.  448.  An  almond ;  where  the  exocarp,  the  portion  of 
the  pericarp  that  represents  the  pulp  of  the  peach,  remains  thin  and  juiceless,  and  at  length 
separates  by  dehiscence  from  the  endocarp,  or  shell. 


ITS    KINDS.  327 

rate  from  each  other,  or  from  a  slender  central  axis,  called  the  Car- 
pophore;  as  in  all  Umbelliferous  plants  (Fig.  735-737),  to  which, 
indeed,  the  name  is  restricted.  Each  separate  carpel,  or  half- 
fruit,  is  termed  a  Hemicarp,  or  Meeicarp,  and  its  inner  face 
the  Commissure. 

607.  A  Caryopsis  is  a  thin  and  membranaceous  pericarp,  like  an 
achenium,  but  adherent  to  the  surface  of  the  seed,  so  as  to  be  in- 
separable from  its  proper  covering.  The  grains  of  Wheat,  Maize, 
and  most  Grasses,  are  examples  (Fig.  463-465). 

608.  A  Utricle  is  a  caryopsis  which  does  not  adhere  to  the  seed  ; 
or  it  is  an  achenium  or  other  one-celled  and  one-seeded  fruit,  with 
a  thin  and  membranous  loose  pericarp,  as  in  Chenopodium  and 
Amarantus. 

609.  A  Nut  is  a  hard  one-celled  and  one-seeded  indehiscent  fruit, 
like  an  achenium,  but  usually  produced  from  an  ovary  of  two  or 
more  cells  with  one  or  more  ovules  in  each,  all  but  a  single  ovule 
and  cell  having  disappeared  during  its  growth  (585) ;  as  in  the 
Hazel,  Beech,  Oak  (Fig.  1044),  Chestnut,  Cocoa-nut,  &c.  The 
nut  is  often  inclosed  or  surrounded  by  a  kind  of  involucre  (393), 
termed  a  Cupule ;  as  the  cup  at  the  base  of  the  acorn,  or  the  burr 
of  the  chestnut. 

610.  A  Samara  is  a  name  applied  to  a  nut,  or  achenium,  having  a 
winged  apex  or  margin;  as  in  the  Birch  and  Elm  (Fig.  1014). 
The  fruit  of  the  Maple  consists  of  two  united  samarse  (Fig.  653). 

611.  A  Berry  is  an  indehiscent  fruit  which  is  fleshy  or  pulpy 
throughout ;  as  the  grape,  gooseberry  (Fig.  707),  and  persimmon 
(Fig.  818).  The  orange,  sometimes  termed  a  Hesperidium,  is 
merely  a  berry  with  a  leathery  rind. 

612.  A  Pome,  such  as  the  apple,  pear,  and  quince,  (Fig.  685- 
688,)  is  a  fruit  composed  of  two  or  more  papery,  cartilaginous,  or 
bony  carpels,  usually  more  or  less  involved  in  a  pulpy  expansion  of 
the  receptacle  or  disk,  and  the  whole  invested  by  the  thickened  and 
succulent  tube  of  the  calyx.  It  may  be  readily  understood  by  com- 
paring a  rose-hip  with  a  haw,  a  quince,  or  an  apple. 

613.  A  Pepo  is  an  indehiscent  fleshy,  or  internally  pulpy  fruit, 
composed  usually  of  three  carpels,  invested  by  the  calyx,  and  with 
a  firm  rind ;  as  the  cucumber,  melon,  and  gourd.  Its  proper 
structure,  which  has  been  variously  misconceived,  may  readily  be 
gathered  from  a  cross-section  of  a  very  young  melon  or  gourd 
(Fig.  449).     The  three  large  placentae  project  from  the  axis  to  the 


328 


THE    FRUIT. 


parietes  of  the  cell,  where  their  two  constituent  parts,  more  or  less 

separated  an^  recurved,  bear  the 
ovules.  As  the  ovary  enlarges,  the 
ends  of  the  placentsB  usually  cohere 
with  the  contiguous  walls,  and  the 
thin  dissepiments  are  at  the  same 
time  obliterated  ;  so  that  the  fruit 
presents  the  deceptive  appearance 
of  a  three-celled  (or,  by  obliteration 
of  the  axis,  a  one-celled)  pericarp, 
with  abnormal  parietal  placentae. 
Sometimes  the  placentae  are  parie- 
tal;  in  that  case  they  are  revolute 

without  meeting  or  cohering  in  the  axis. 

614.  A  Capsule  is  a  general  term  for  all  dry  and  dehiscent  pods 
resulting  from  a  compound  ovary,  whether  opening  by  valves  (593, 
Fig.  621,  &c.),  or  bursting  irregularly,  as  in  Lobelia,  or  shedding 
the  seeds  through  chinks  or  pores,  as  in  the  Poppy. 

615.  A  Silique  is  a  two-valved  capsule,  rendered  two-celled  by  a 
false  partition  stretched  between  the  parietal  placentae  (552),  from 
which  the  valves  separate ;  as  in  all  Cruciferous  plants  (Fig.  527), 
to  which  family  it  is  confined.  A  short  and  broad  silique  is  called 
a  SiLiCLE  'y  as  in  the  Shepherd's  Purse  or  Capsella  (Fig.  532)  = 

616.  A  Pyxidium,  or  Pyxis,  is  a  capsule  that  opens  transversely  by 
a  lid  or  cover,  as  already  explained  (600). 

617.  Anthocarpous  Fruits  are  those  which,  in  addition  to  the  peri- 
carp, have  an  accessory  covering  derived  from  some  exterior  or- 
gan, which,  however,  does  not  cohere  with  the  ovary  in  the  fruit ; 
as  the  nut-like  fruit  of  Mirabilis,  the  hard  outer  envelope  of  which 
is  the  indurated  and  persistent  base  of  the  tube  of  the  calyx,  which 
was  perfectly  free  in  the  blossom.  And  the  berry-like  fruit  of 
Shepherdia  consists  of  a  fleshy  calyx-tube,  inclosing  a  free  nut-like 
pericarp.  Instances  of  this  kind  are  common  among  what  are 
called 

618.  Multiple  or  Collective  Fruits ;  or  those  which  result  from  the 
aggregation  of  several  flowers  into  one  body  or  mass.  They  are, 
in  fact,  dense  forms  of  inflorescence,  with  the  fruits  or  floral  enve- 
lopes matted  together  or  coherent  with  each  other ;  as  in  the  pine- 


FIG.  449.    Section  of  the  ovary  of  the  Gourd;  and  450,  a  diagram  of  one  of  ita  constituent 
carpels. 


THE    SEED.  329 

apple,  the  mulberry  (Fig.  244),  &c.  The  grains  of  the  latter  are 
not  the  ovaries  of  a  single  flower,  like  those  of  the  blackberry  (Fig. 
680),  but  belong  to  as  many  separate  flowers;  and  the  pulp  of 
these  belongs  to  the  floral  envelopes  instead  of  the  pericarp  (583). 
The  fig  results  from  a  multitude  of  flowers  concealed  in  a  hollow 
flower-stalk,  if  it  may  be  so  called,  which  becomes  pulpy  and  edi- 
ble (Fig.  241-243).  Thus  the  fruit  seems  to  grow  directly  from 
the  branch  without  being  preceded  by  a  flower.  In  the  Partridge- 
berry  (Mitchella  repens),  and  in  several  species  of  Lonicera  (Fig. 
741),  the  ovaries  of  two  flowers  are  uniformly  united,  so  as  to  form 
a  double  berry  ;  just  as  twin  apples  or  cherries  are  sometimes  acci- 
dentally produced. 

619.  A  Cone,  or  Strobile,  is  a  collective  fruit  of  the  Pine  and  Cy- 
cas  Families  (Fig.  395,  403) ;  each  scale  representing  an  open 
carpel  (375),  bearing  one  or  more  naked  seeds. 

620.  The  cone  of  a  Magnolia  is,  however,  entirely  different, 
consisting  of  the  numerous  aggregated  carpels  of  a  single  flower, 
crowded  and  persistent  on  an  elongated  receptacle. 


CHAPTER    XI. 

OF    THE    SEED. 

Sect.  I.     Its  Structure  and  Parts. 

621.  The  Seed,  like  the  ovule  (561),  of  which  it  is  the  fertilized 
and  matured  state,  consists  of  a  Nucleus,  usually  inclosed  within 
two  Integuments. 

622.  Its  Integuments.  The  outer,  or  proper  seed-coat,  corre- 
sponding to  the  exterior  coat  (563)  of  the  ovule,  is  variously  termed 
the  Episperm,  Spermoderm,  or  more  commonly  the  Testa  (Fig. 
451,  h).  It  varies  greatly  in  texture,  from  membranaceous  or 
papery  to  crustaceous  or  bony  (as  in  the  Papaw,  Nutmeg,  &c.), 
and  also  in  form;  being  sometimes  closely  applied  (conformed)  to 
the  nucleus,  and  in  other  cases  loose  and  cellular  (as  in  Pyrola, 
Fig.  810,  and  SuUivantia,  Fig.  725),  or  expanded  into  wings  (as  in 
the  Catalpa  and  Bignonia),  which  render  the  seeds  buoyant,  and 

28* 


THE    SEED. 

facilitate  their  dispersion  by  the  wind  ;  whence  winged  seeds  are 
only  met  with  in  dehiscent  fruits.  For  the  same  purpose,  the 
testa  is  sometimes  provided  with  a  tuft  of  hairs  at  one  end, 
termed  a  Coma  ;  as  in  Epilobium,  Asclepias,  or  Milkweed  (Fig. 
963),  and  Apocynum  (Fig.  954).  In  the  Cotton-plant,  the 
whole  testa  is  covered  with  long  wool.  It  should  likewise  be 
noticed,  that  the  integument  of  numerous  small  seeds  (and  also 
seed-like  achenia)  is  furnished  with  a  coating  of  small  hairs  con- 
taining spiral  threads  (one  form  of  which  is  represented  in  Fig. 
31),  and  usually  appressed  and  confined  to  the  surface  by  a  film 
of  mucilage.  When  the  seed  is  moistened,  the  mucilage  softens, 
and  these  hairs  shoot  forth  in  every  direction.  They  are  often 
ruptured,  and  the  extremely  attenuated  elastic  threads  they  contain 
uncoil,  and  are  protruded  in  the  greatest  abundance  to  a  very  con- 
siderable length.  This  minute  mechanism  subserves  an  obvious 
purpose  in  fixing  these  small  seeds  to  the  moist  soil  upon  which 
they  lodge,  when  dispersed  by  the  wind.  Under  the  microscope, 
these  threads  may  be  observed  on  the  seeds  of  most  Polemonia- 
ceous  plants,  and  the  achenia  of  Labiate  and  Composite  plants,  as, 
for  example,  in  many  species  of  Senecio,  or  Groundsel. 

623.  The  inner  integument  of  the  seed,  called  the  Tegmen  or 

a  Endopleura,   although    frequently  very 

obvious  (as  in  Fig.  451),  is  often  indis- 
tinguishable from  its  being  coherent  with 
the  testa,  or  else  altogether  wanting. 
Nor  when  present  does  it  always  origi- 
nate from  the  secundine  or  inner  coat  of 
the  ovule  (563).  In  the  Hypericum  Family  (Fig.  454),  in  the 
Pea  Family,  and  probably  in  a  great  many  other  cases,  especially 
where  it  is  tumid  or  fleshy,  or  where  it  adheres  firmly  to  the  albu- 
men, it  doubtless  consists  of  the  remains  of  the  nucleus  of  the 
ovule,  or  of  the  embryo  sac. 

624.  The  stalk  of  the  seed,  as  in  the  ovule  from  which  it  origi- 
nated, is  called  the  Funiculus  (Fig.  452).  The  scar  left  on  the 
face  of  the  seed  by  its  separation  from  the  funiculus  at  maturity  is 
termed  the  Hilum.  The  relation  of  the  hilum  to  the  chalaza,  mi- 
cropyle  (563),  and  other  parts  of  the  seed,  has  been  sufliciently 

FIG.  451.  Vertical  magnified  section  of  the  (anatropous)  seed  of  the  American  Linden :  a, 
the  hilum;  b,  the  testa;  c,  the  tegmen;  d,  the  albumen;  e,  the  embryo.  452.  Vertical  section 
of  the  (orlhotropous)  seed  of  Helianthemum  Canadense:  a,  the  funiculus. 


ITS    STRUCTURE    AND    PARTS.  331 

indicated  when  considering  the  structure  of  the  ovule.  The  cha- 
laza  and  raphe  (567),  when  present,  are  commonly  obvious  in  the 
mature  seed,  as  well  as  in  the  ovule  (Fig.  455,  b).  The  terms  ortho- 
tropous,  anatropous,  campylotropous,  &;c.,  originally  applied  to  the 
ovules,  are  extended  to  the  seeds  which  result  from  them  ;  so  that 
we  may  say.  Seeds  anatropous,  as  well  as  Ovules  anatropous,  &c. 

625.  Aril  (Arillus).  Some  seeds  are  furnished  with  a  covering, 
usually  incomplete  and  of  a  fleshy  texture,  wholly  exterior  to  their 
proper  integuments,  arising  from  an  expansion  of  the  apex  of  the 
seed-stalk,  or  funiculus,  or  of  the  placenta  itself  when  there  is  no 
manifest  seed-stalk.  This  is  called  the  Aril.  It  forms  the  pulpy 
envelope  of  the  seed  of  Podophyllum,  Euonymus,  and  Celastrus, 
or  a  mere  lateral  scale  in  Turnera,  or  a  tough,  lacerated  body, 
known  by  the  name  of  mace^  in  the  Nutmeg.  In  the  White  Water- 
Lily  it  is  a  thin,  cellular  bag,  open  at  the  end  (Fig.  453). 
It  does  not  appear  in  the  ovule,  but  is  developed  subse- 
quent to  fertilization,  during  the  growth  of  the  seed.  Of 
the  same  nature  is  the  Caruncle  which  grows  from  the 
hilum  in  Polygala,  forming  a  loose  lateral  appendage. 
Strictly  speaking,  it  is  to  be  distinguished  from  the  Stro- 
PHiOLE,  the  latter  being  a  cellular  growth  from  the  micro- 
pyle  ;  but  the  two  are  not  well  discriminated.  A  similar  cellular 
growth  takes  place  on  the  raphe  of  the  Bloodroot,  of  the  Prickly 
Poppy,  and  of  Dicentra,  forming  a  conspicuous  crest  on  the  whole 
side  of  the  seed. 

626.  The  Nucleus,  or  kernel  of  the  seed,  consists  of  the  Albumen, 
when  this  substance  is  present,  and  the  Embryo. 

627.  The  Albumen  (Fig.  451,  d,  456,/)  —  also  variously  named 

the  Perisperm  or  the  Endosperm  — 

be  c 

which  forms  the  floury  part  of  the 
seed  in  our  various  kinds  of  grain, 
consists  of  whatever  portion  of  the  tis- 
sue of  the  ovule  persists,  and  becomes 
loaded  with  nutritive  matter  accumu- 
lated in  its  cells,  —  sometimes  in  the  form  of  starch-grains  prin- 

FIG.  453.    Seed  of  Nymphaea  (White  Water-Lily),  in  its  membranaceous  sac-like  aril. 

FIG.  454.  Vertical  section  of  a  seed  of  Elodea  Virginica,  showing  the  two  integuments  of 
the  seed,  and  the  embryo. 

FIG.  455.  Seed  of  Delphinium  tricome  (anatropous),  enlarged  :  a,  the  hilum ;  h,  the  raphe ; 
c,  the  chalaza.  456.  Vertical  section  of  the  same:  c,  the  chalaza;  d,  the  testa;  c,  the  tegmen; 
/,  the  albumen ;  g,  the  minute  embryo  near  the  hilum,  a. 


332  THE    SEED. 

cipally,  as  in  wheat  and  the  other  cereal  grains,  sometimes  as  a 
continuous,  often  dense,  incrusting  deposit,  as  in  the  cocoa-nut,  the 
date,  the  coffee-grain,  &c.  When  it  consists  chiefly  of  starch- 
grains,  and  may  readily  be  broken  down  into  a  powder,  it  is 
said  to  he  farinaceous,  or  mealy  ^  as  in  the  cereal  grains  generally, 
in  buckwheat,  &c.  When  a  fixed  oil  is  largely  mixed  with  this, 
it  becomes  oily,  as  in  the  seed  of  the  Poppy,  (fee. ;  when  more 
compact,  but  still  capable  of  being  readily  cut  with  a  knife,  it  is 
fleshy,  as  in  the  Barberry,  &c. ;  when  it  chiefly  consists  of  muci- 
lage or  vegetable  jelly,  as  in  the  Morning  Glory  and  the  Mallow,  it 
is  said  to  be  mucilaginous ;  when  dense  and  tough,  so  as  to  offer 
considerable  resistance  to  the  knife,  as  in  the  Coffee,  the  Blue  Co- 
hosh (Leontice),  &c.,  it  is  corneous^  that  is,  of  the  texture  of  horn. 
Between  these  all  gradations  occur.  Commonly  the  albumen  is  a 
uniform  deposit.  But  in  the  nutmeg,  and  in  the  seeds  of  the  Pa- 
paw  (Fig.  494)  and  of  all  plants  of  the  Custard  Apple  Family,  it 
presents  a  wrinkled  or  variegated  appearance,  owing  to  numerous 
transverse  divisions,  probably  caused  by  inflections  of  the  embryo 
sac ;  in  these  cases  the  albumen  is  said  to  be  ruminated. 

628.  As  already  intimated,  the  albumen  may  originate  from 
new  tissue  formed  either  within  the  embryo  sac  (579),  which  is 
probably  the  more  common  case  ;  or  in  the  nucleus  of  the  ovule 
exterior  to  the  embryo  sac,  which  is  certainly  the  case  in  the 
Water-Lily  and  its  allies  (the  Water-shield,  &c..  Fig.  518),  and  in 
Saururus,  for  here  the  thickened  embryo  sac  persists  within  or  at 
one  extremity  of  the  copious  albumen ;  or  both  kinds  may  co- 
exist. In  the  first-named  case,  if  any  of  the  proper  tissue  of  the 
nucleus  remains,  it  is  condensed  and  forms  the  inner  integument  of 
the  seed,  or  becomes  confluent  with  it  (623). 

629.  The  office  to  which  the  albumen  is  subservient  is  the  nour- 
ishment of  the  embryo  when  it  begins  to  develope  into  a  plant.  It 
is  a  store  of  nutritive  matter,  in  a  very  compact  or  condensed 
form,  accumulated  around  or  next  the  embryo,  which  feeds  upon  it 
in  germination,  until  it  is  so  far  developed  that  it  can  obtain  and 
assimilate  food  for  itself  (118).  The  name,  therefore,  which  was 
applied  to  it  by  Ggertner,  from  its  analogy  to  the  albumen  or  white 
of  the  egg  of  birds,  is  not  inappropriate,  although  the  comparison 
will  not  bear  to  be  carried  out  in  detail.  As  would  be  expected 
from  its  functions,  the  albumen  is  the  more  copious  in  the  seed  in 
proportion  as  the  embryo  is  smaller  and  feebler,  or  less  developed. 
(Fig.  456,  compared  with  Fig.  461,  &c.) 


THE    EMBRYO.  333 

630.  When  the  embryo,  instead  of  being  arrested  in  its  growth 
in  the  seed  while  yet  minute  and  rudimentary,  developes  so  far  as 
to  exhibit  its  component  organs,  and  form  its  cotyledons  into  evi- 
dent, but  usually  more  or  less  thickened  leaves  (as  in  the  Almond, 
Fig.  457,  458,  the  Bean,  the  Maple,  Fig.  105,  &c.),  it  absorbs  the 
nutritive  matter  of  the  nucleus  immediately  in  the  course  of  its 
growth  ;  either  completely,  as  in  the  examples  just  adduced,  or  par- 
tially, so  as  to  leave  a  thin  albumen  (as  in  Polygala,  the  Bladder- 
nut,  &c.).  In  such  exdlhuminous  seeds  (viz.  those  entirely  desti- 
tute of  albumen),  the  requisite  store  of  nourishment,  whether  of 
farinaceous,  mucilaginous,  or  oily  matter,  or  frequently  of  all  these 
kinds  combined  (as  in  flax-seed,  the  walnut,  the  almond,  &c.), 
is  lodged  in  the  embryo,  chiefly  in  the  cotyledons,  instead  of  being 
accumulated  around  it.  Here  the  embryo  occupies  the  whole  cav- 
ity, or  forms  the  whole  kernel  of  the  seed,  and  is  directly  invested 
by  the  integuments  (Fig.  454,  1047) ;  while  in  alhuminous  seeds, 
the  albumen  is  interposed  between  them,  at  least  on  one  side 
(Fig.  463,  559),  and  more  commonly  on  all  sides  (Fig.  451,  452). 

631.  The  Embryo,  being  an  initial  plantlet  or  new  individual,  is  of 
course  the  most  important  part  of  the  seed  ;  and  to  its  production, 
protection,  and  support,  all  the  other  parts  of  the  fruit  and  flower 
are  subservient.  It  becomes  a  plant  by  the  mere  development  of 
its  parts :  it  therefore  possesses,  in  a  rudimentary  or  undeveloped 
state,  all  the  essential  organs  of  vegetation,  namely,  a  root,  stem,  and 
leaves,  ai5  has  already  been  explained  (113,  118,  Fig.  105-107). 
In  numerous  cases,  as  in  the  Maple,  the  Linden  (Fig.  626),  and  the 
Convolvulus  (Fig.  927),  &c.,  these  several  parts  are  perfectly 
distinguishable  in  the  seed ;  and  the  seed- 
leaves  are  already  foliaceous :  sometimes 
they  are  large,  but  thickened  by  the  nourish- 
ing matter  they  contain,  as  in  the  Almond 
(Fig.  457),  and  the  Oak  (Fig.  1047).  Fre- 
quently, however,  we  only  observe  an  oblong 
body,  cleft  or  barely  two-lobed  at  one  end, 

•       1^'  A^  A        y  •  •  •  -1  T  457  458 

as  m  tig.  454  ;  but  m  germmation  the  undi- 
vided extremity  elongates  into  a  root,  the  two  lobes  at  the  opposite 
end  disclose  their  real  nature  by  expanding  into  leaves,  and  the 
stem  rises  between  them. 

FIG.  457.    Embryo  (the  whole  kernel)  of  the  Almond.    45S.  The  same,  with  one  of  the  co- 
tyledons removed,  showing  the  plumule,  a. 


SSI  THE    SEED. 

632.  The  two  lobes,  or  rudiments  of  the  first  pair  of  leaves,  are 
termed  Cotyledons  ;  the  bud,  which,  if  not  actually  visible  in  the 
seed,  as  in  the  Almond  (Fig.  458,  a),  appears  between  them  when 
germination  commences,  is  called  the  Plumule  ;  and  the  portion 
below,  which  gives  rise  to  the  root,  is  named  the  Radicle. 

633.  In  these  illustrations,  we  have  assumed  the  embryo  with  a 
pair  of  cotyledons  to  be  the  typical,  as  it  is  the  most  common  form, 
occurring  as  it  does  in  all  the  families  of  Exogenous  plants  (186). 
Hence  the  latter  are  also  called  Dicotyledonous  Plants  (188). 

634.  But  in  all  Endogenous  plants  only  one  cotyledon  appears, 
or  at  least  only  one  on  the  primary  node  ;  if  two  rudimentary 
leaves  are  present,  one  of  them  is  alternate  with  the  other,  and  be- 
longs to  a  second  node.  Hence  Endogens  are  also  termed  Mono- 
coTYLEDONous  Plants.  The  monocotyledonous  embryo  does 
not  usually  present  the  same  manifest  distinction  into  radicle, 
cotyledons,  and  plumule,  as  the  dicotyledonous  ;  but  often  appears 
like   a   homogeneous    and    undivided    cylindrical    or  club-shaped 

body,  as  in  Triglochin  (Fig.  460).  In 
this,  as  in  many  other  monocotyledo- 
nous embryos,  however,  a  vertical  slit, 
or  chink,  is  observed  near  the  radicular 
extremity,  through  which  the  plumule 
is  protruded  in  germination.  If  the 
embryo  be  divided  parallel  with  this 
slit,  the  plumule  is  brought  into  view ; 
as  in  Fig.  461.  If  a  horizontal  section  be  made  at  this  point  (as 
in  Fig.  462),  the  cotyledon  is  found  to  be  wrapped  around  the  in- 
closed plumule,  sheathing  it,  much  as  the  bud  and  the  younger  parts 
of  the  stem  are  sheathed  by  the  bases  of  the  leaves  in  most  mono- 
cotyledonous plants.  The  plumule  is  more  manifest  in  Grasses, 
especially  in  the  cereal  grains,  and  more  complex,  exhibiting  the 
rudiments  of  several  concentric  leaves,  or  of  a  strong  bud,  previous 
to  germination  (Fig.  463-465).  In  many  cases,  however,  no  dis- 
tinction of  parts  is  apparent  until  germination  commences ;  as  in 
the  Onion,  the  Lily,  &c. 

635.  The  more  common  of  the  extremely  varied  forms  under 

FIG.  459.  Seed  of  Triglochin  palustre ;  the  raphe,  leading  to  the  strong  chalaza  at  the  sum- 
mit, turned  towards  the  eye.  460.  The  embryo  detached  from  the  seed-coats,  showing  the  lon- 
gitudinal chink  at  the  base  of  the  cotyledon  ;  the  short  part  below  is  the  radicle.  461.  Same, 
with  the  chink  turned  laterally,  and  half  the  cotyledon  cut  away,  bringing  to  view  the  plumule 
concealed  within.    462.  A  cross-section  through  the  plumule,  more  magnified. 


THE    EMBRYO. 


335 


which  the  embryo  occurs  may  readily  be  gathered  from  the  nu- 
merous illustrations  scattered  through  this  volume  ;  which  need  not 
be  specially  enumerated.  Its  position  as  respects  the  albumen, 
when  that  is  present,  is  also  various.  Although  more  commonly 
in  the  axis,  it  is  often  excentric,  or  even  external  to  the  albumen, 
as  in  all  Grasses  (Fig.  463-465),  in  Polygonum  (Fig.  787),  &c. 


When  external  or  nearly  so,  and  curved  circularly  around  the 
albumen,  as  in  Fig.  559,  565,  995,  and  generally  in  the  fami- 
lies from  which  these  illustrations  are  taken,  it  is  called  peripheric. 
When  the  embryo  is  bent  so  that  the  radicle  is  placed  against  the 
edges  of  the  cotyledons,  the  latter  are  said  to  be  accumbent  (Fig. 
529)  ;  or  when  the  radicle  rests  against  the  back  of  one  of  them 
(Fig.  538),  they  are  called  incumbent. 

636.  The  situation  of  the  embryo  with  respect  to  the  base  and 
apex  of  the  seed  is  so  far  uniform,  that  the  radicle  always  points  to 
the  micropyle,  as  already  mentioned.  As  the  nature  of  the  seed 
may  usually,  after  some  practice,  be  readily  determined  by  exter- 
nal inspection,  so  the  situation  of  the  embryo  within,  consequently, 
may  often  be  inferred  without  actual  dissection. 

637.  The  direction  of  the  embryo  with  respect  to  the  pericarp  is 
also  particularly  noticed  by  systematic  writers ;  who  employ  the 
terms  ascending,  or  radicle  superior,  when  the  latter  points  to  the 
apex  of  the  fruit ;  descending,  or  radicle  inferior,  when  it  points 
to  its  base;  centripetal,  when  the  radicle  is  turned  towards  the 
axis  of  the  fruit ;  centrifugal,  if  towards  the  sides ;  and  vague, 
when  it  bears  no  evident  or  uniform  relation  of  this  kind  to  the 
pericarp. 

638.  Sometimes  the  two  cotyledons  of  a  dicotyledonous  embryo 


FIG.  463.  Vertical  section  of  a  grain  of  Indian  Corn,  passing  through  the  embryo:  c,  the 
cotyledon  ;  p,  the  plumule  ;  r,  the  radicle.  (A  highly  magnified  portion  of  the  albumen,  which 
makes  up  the  principal  bulk  of  the  grain,  is  shown  in  Fig.  52,  p.  57.)  464.  Similar  section  of 
a  grain  of  Rice.  465.  Vertical  section  of  an  Oat-grain:  a,  the  albumen;  c,  the  cotyledon;  p, 
the  plumule  ;  and  r,  the  radicle  of  the  embryo. 


336  THE    SEED. 

are  consolidated  or  more  or  less  coherent  by  their  contiguous  faces 
into  one  mass,  or  slyq  confer  ruminate,  as  in  the  Horsechestnut  (Fig. 
661). 

639.  In  the  Cuscuta,  or  Dodder,  which  never  produces  foliage, 
the  embryo  is  also  entirely  destitute  of  seed-leaves  or  cotyledons 
(Fig.  122  —  124).  Here  these  organs  are  suppressed  in  an  embryo 
of  considerable  size ;  but  in  most  such  parasites,  the  embryo  is 
very  minute,  as  well  as  reduced  to  the  greatest  degree  of  simpli- 
city, and  seems  to  remain  until  germination  in  a  very  rudimentary 
state. 

640.  On  the  other  hand,  the  embryo  assumes  the  highest  com- 
plexity in  Pines  and  many  other  Coniferous  plants  (400) ;  where 
the  cotyledons  as  they  form  are  increased  in  number,  from  two  to 
four,  six,  or  even  fifteen,  by  collateral  chorisis  (455) ;  here  the 
embryo  is  jpolycolyledonous. 

Sect.  II.     Germination. 

641.  Our  narrow  limits  prevent  us  from  illustrating  the  vari- 
ous arrangements  for  the  natural  dissemination  of  seeds,  which 
would  form  the  subject  of  an  interesting  chapter ;  and  from  consid- 
ering the  circumstances  under  which  the  embryo  retains  its  vital- 
ity, in  many  species  ordinarily  for  a  few  months  only,  in  some 
perhaps  for  many  centuries.*  We  must  very  briefly  notice  the 
conditions  under  which  this  latent  vitality  is  called  into  activity, 
and  the  embryo  developes  into  a  plant. 

642.  The  conditions  requisite  to  germination  are  exposure  to 


*  It  is  well  known  that  seeds  which  have  been  kept  for  sixty  years  have 
germinated  ;  and  it  seems  that  grains  of  wheat,  taken  from  ancient  mummies 
under  circumstances  which  leave  little  doubt  of  their  high  antiquity,  have 
been  made  to  germinate;  but  in  these  cases  there  are  several  sources  of  possi- 
ble deception.  Dr.  Lindley  records  the  remarkable  case  of  some  Raspberries, 
"raised  in  the  garden  of  the  Horticultural  Society  from  seeds  taken  from  the 
stomach  of  a  man,  whose  skeleton  was  found  thirty  feet  below  the  surface  of 
the  earth,  at  the  bottom  of  a  barrow  which  was  opened  near  Dorchester.  He 
had  been  buried  with  some  coins  of  the  Emperor  Hadrian;  and  it  is  therefore 
probable  that  the  seeds  were  sixteen  or  seventeen  hundred  years  old.''  Most 
seeds,  when  buried  deep  in  the  soil,  where  they  are  subject  to  a  uniform  and 
moderate  temperature,  and  removed  from  the  influence  of  the  air  and  light, 
are  in  a  favorable  state  for  the  preservation  of  vitality,  and  will  germinate 
when  brought  to  the  surface  after  a  long  interval. 


GERMINATION.  337 

moisture  and  to  a  certain  amount  of  heat,  varying  from  50°  to  80° 
(Fahrenheit)  for  the  plants  of  temperate  climates,  to  which  must 
be  added  a  free  communication  with  the  air.  Direct  light,  so  es- 
sential to  subsequent  vegetation,  is  unnecessary,  if  not  unfavorable 
to  germination.  The  degree  of  heat  required  to  excite  the  latent 
vitality  of  the  embryo  is  nearly  uniform  in  the  same  species,  but 
widely  different  in  different  plants  ;  since  the  common  Chickweed 
will  germinate  at  a  temperature  not  far  above  the  freezing-point  of 
water,  while  the  seeds  of  many  tropical  plants  require  a  heat  of 
90°  to  110°  (Fahrenheit)  to  call  them  into  action,  and  are  often 
exposed  to  a  considerably  higher  temperature.  Seeds  are  in  the 
most  favorable  condition  for  germination  in  spring  or  summer, 
when  loosely  covered  with  soil,  which  excludes  the  light  while  it 
freely  admits  the  air,  moistened  by  showers,  and  warmed  by  the 
rays  of  the  sun.  The  water  which  is  slowly  absorbed  softens  all 
the  parts  of  the  seed  ;  the  embryo  swells,  and  bursts  its  envelopes  ; 
the  radicle  is  protruded,  and,  taking  a  downward  direction,  fixes  it- 
self in  the  soil ;  while  the  other  extremity  elongates  in  the  opposite 
direction,  bringing  the  cotyledons  (except  when  these  remain  un- 
der ground,  as  in  the  Pea,  the  Horsechestnut,  Wheat,  (fee.)  and  the 
plumule,  or  growing  apex  of  the  young  stem,  to  the  surface,  when 
the  primordial  leaves  expand  in  the  air.  As  soon  as  the  root  and 
leaves  are  developed,  each  in  their  appropriate  medium,  the  pro- 
cess of  germination  is  finished  ;  and  the  plant,  deriving  through 
them  its  nourishment,  continues  to  grow  in  the  manner  already 
described  (113). 

643.  The  nourishment  which  the  embryo  requires  during  germf- 
nation  is  furnished  by  the  starch,  &c.,  of  the  albumen  (627),  when 
this  substance  is  present  in  the  seed  ;  or  by  starchy  or  other  matter 
accumulated*  in  its  own  tissue  (630).  But  as  starch  is  insoluble  in; 
cold  water,  certain  chemical  changes  are  necessary  to  bring  it  into 
a  fluid  state,  so  that  it  may  nourish  the  embryo.  These  changes 
are  incited  by  the  proteine  compounds,  or  neutral  azotized  products- 
(354),  which  are  largely  accumulated  in  the  seed,  whether  in  the 
albumen  or  in  the  embryo  itself  (356),  and  which  here,  as  else- 
where, take  the  initiative  in  all  the  transformations  of  vegetable- 
matter  (27).  Here,  just  as  in  growth  from  a  bulb  or  tuber,  the 
changes  essentially  consist  in  the  transformation  of  the  starch,, 
first  into  dextrine,  or  gum,  and  thence  into  sugar  (350),  a  part  of 
which  is  destroyed  by  resolution,  first  into  acetic  acid,  and  finally 
29 


338  THE    SEED. 

into  -carbonic  acid  and  water,  with  the  abstraction  of  oxygen  from 
the  air,  and  the  evolution  of  heat  (372),  while  the  remainder  is 
rendered  directly  subservient  to  the  growth  of  the  plantlet.  The 
reason  why  light,  so  essential  to  subsequent  growth,  impedes  or 
prevents  incipient  germination,  becomes  evident  when  we  remem- 
ber that  it  incites  the  decomposition  of  carbonic  acid,  and  the  fixa- 
tion of  carbon  by  the  plant  (344-350)  ;  while  germination  is  ne- 
cessarily attended  by  an  opposite  transformation,  namely,  the  de- 
struction of  a  portion  of  organized  matter,  with  the  evolution  of 
carbonic  acid. 

644.  In  most  Dicotyledonous  plants,  the  cotyledons  rise  out  of 
the  ground,  and  perform  more  or  less  perfectly  the 
office  of  leaves,  until  those  of  the  plumule  expand 
(Fig.  100-  107) :  but  when  the  cotyledons  are  very 
thick  and  fleshy,  as  in  the  Horsechestnut,  the  Pea, 
the  Oak,  &c.,  they  serve  merely  as  reservoirs  of 
nourishment,  and  remain  under  ground,  that  is,  are 
hypogcBous  in  germination,  the  first  leaves  which  ap- 
pear being  those  of  the  plumule.  This  is  also  the 
case  in  all  Monocotyledonous  plants ;    in  which  the 

cotyledon  remains  within  the  integuments  of  the 
seed,  while  the  radicle  and  plumule  together  pass  out  at  or  near 
the  micropyle,  as  shown  in  the  germinating  seed  of  Scirpus 
(Fig.  466). 

645.  Seeds  may  casually  germinate  while  attached  to  the  parent 
plant,  especially  such  as  are  surrounded  with  pulp,  like  those  of 
the  Cucumber  and  Melon.  The  process  is  liable  to  commence  in 
wheat  or  other  grain,  when  protracted  warm  and  rainy  weather 
occurs  at  the  period  of  ripening ;  and  the  albumen  becomes  gluti- 
nous and  sweet,  from  the  partial  transformation  of  the  starch  into 
gum  and  sugar.  In  the  Mangrove,  which  forms  dense  thickets 
along  tropical  coasts,  germination  commonly  takes  place  in  the 
pericarp  while  the  fruit  remains  on  the  tree  ;  and  the  radicle,  pier- 
cing the  integuments  which  inclose  it,  elongates  in  the  air,  until  it 
reaches  and  fixes  itself  in  the  soft  maritime  mud,  where  such 
trees  usually  grow  (131) ;  such  a  plant  being,  as  it  were,  vivip- 
arous.    This  very  naturally  takes  place,  also,  in  the  seeds  of  hy- 

FIG.  466.  The  germinating  seed  of  Scirpus,  a  Monocotyledonous  plant:  a,  the  cotyledon, 
remaining  within  the  albumen,  6,  inclosed  in  the  pericarp,  c ;  from  which  the  plumule  (d) 
elongates. 


CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS.  339 

pogcEous  fruits,  namely,  when  the  fruit  is  produced  on  radical 
branches,  beneath  the  surface  of  the  soil,  as  in  the  Peanut,  in 
Amphicarpsea,  Polygala  polygama,  and  many  other  plants. 


^*^  646.  Cryptogamous  or  Flowerless  Plants.  The  general  morphol- 
ogy of  these  simpler  forms  of  vegetation  has  been  very  briefly  ad- 
verted to  (in  Chapter  11.)  in  sketching  the  progressive  development 
of  the  plant,  from  those  of  a  single  cell  or  a  simple  congeries  of  cells 
up  to  those  which  exhibit  the  completed  type  of  vegetation.  Taken 
collectively,  we  distinguish  this  lower  series  of  the  vegetable  king- 
dom by  negative  characters  only ;  saying  that  they  do  not  bear 
true  flowers  (consisting  essentially  of  stamens  and  pistils),  and  ac- 
cordingly do  not  produce  seeds,  or  bodies  consisting  of  a  distin- 
guishable embryo  plantlet,  developed  through  fertilization  in  an 
ovule.  Their  spores  (101),  or  the  bodies  produced  in  their  fructifi- 
cation by  which  they  are  propagated,  and  which  therefore  answer  to 
seeds,  are  single  cells,  in  most,  if  not  in  all  cases.  These,  as  they 
germinate  in  the  soil,  or  whatever  medium  they  grow  in,  undergo 
a  development  at  the  time  of  their  germination  apparently  analo- 
gous to  that  of  the  embryonal  vesicle  (577)  during  its  development 
into  the  embryo  in  the  ovule  of  a  Phsenogamous  plant.  But  the 
organs  of  fructification,  and  the  modes  in  which  the  spores  are 
produced,  are  so  exceedingly  diverse  in  the  different  families 
of  Cryptogamous  plants,  that  botanists  are  as  yet  unable  to  re- 
duce them  to  a  common  formula  or  type,  as  they  have  so  effect- 
ually done  in  Phsenogamous  vegetation.  Each  great  family  of 
the  Cryptogamia  seems  to  be  formed  on  a  plan  peculiar  to  itself; 
each  presents  a  special  morphology,  and  has  to  be  independently 
treated,  —  with  considerable  fulness  too,  and  much  particularity  of 
illustration,  if  the  subject  is  to  be  made  intelligible  to  the  unprac- 
tised student.  Moreover,  the  functions  of  the  different  organs  are 
as  unsettled  as  their  morphology.  Unable,  therefore,  to  do  any 
justice  to  so  complex  and  difficult  a  subject  within  our  narrow  lim- 
its, we  postpone  our  account  of  them  to  the  systematic  part  of  the 
work,  at  the  close  of  which  the  leading  characters  of  the  several 
orders  of  Cryptogamic  plants,  and  the  principal  terms  applied  to 
their  diflferent  organs,  will  be  succinctly  illustrated. 


340  SPONTANEOUS    MOVEMENTS    IN    PLANTS. 


CHAPTER    XII. 

OF    THE     SPONTANEOUS     MOVEMENTS    WHICH     PLANTS     EXHIBIT. 

647.  Plants,  like  other  living  beings,  execute  certain  movements, 
or  changes  in  the  position  of  their  parts,  through  some  inherent 
powers,  which,  though  far  less  striking  and  less  varied  than  in  ani- 
mals, and  of  a  nature  wholly  different  from  muscular  motion,  must 
not  be  overlooked. 

648.  The  Special  Directions  which  the  organs  of  the  plant  assume 
belong  to  this  class  of  manifestations,  although  the  movements  are 
mostly  much  too  slow  to  be  directly  observed.  Among  these  are  the 
invariable  descent  of  the  root  in  germination,  the  invariable  ascent 
of  the  stem  into  the  light  and  air,  and  the  turning  of  branches  and 
the  upper  surface  of  leaves  towards  the  light  (113,  139,  294). 
Although  these  movements  are  incited  by  common  physical  agents 
(just  as  analogous  kinds  of  movements  are  in  animals),  and  can- 
not be  the  result  of  any  thing  like  volition,  yet  nearly  all  of  them 
are  inexplicable  upon  mechanical  principles.  Some  of  them,  at 
least,  are  spontaneous  motions  of  the  plant  or  organ  itself,  due  to 
some  inherent  power,  which  is  merely  put  in  action  by  light,  attrac- 
tion, or  other  external  influences. 

649.  The  external  agencies  concerned  in  the  descent  of  the  root 
and  the  rise  of  the  stem  seem  chiefly  to  be, —  1st,  the  attraction  of 
the  earth  acting  upon  the  root ;  and  2d,  the  influence  of  light  upon 
the  stem.  The  influence  of  gravitation,  or  of  a  similar  force,  was 
proved  by  the  celebrated  experiment  of  Mr.  Knight ;  who  caused 
the  seeds  of  the  Bean  to  germinate  in  a  quantity  of  Moss  fastened 
to  the  circumference  of  a  wheel,  which  was  made  to  revolve  verti- 
cally at  a  rapid  rate  ;  where  the  seeds  were  subjected  to  the  cen- 
trifugal force  alone,  acting  like  that  of  gravitation,  but  in  the  oppo- 
site direction.  On  examination,  after  some  days,  the  young  root 
and  stem  were  found  to  have  taken  the  direction  of  the  axis  of  ro- 
tation ;  the  former  being  turned  towards  the  circumference,  and 
the  latter  towards  the  centre  of  the  wheel.  The  same  result  took 
place  when  the  wheel  was  made  to  revolve  horizontally  with  con- 
siderable rapidity  ;  but  when  the  velocity  was  moderate,  the  roots 
were  directed  obliquely  downwards  and  outwards,  and  the  stems 


THEIR    SPECIAL    DIRECTIONS.  341 

obliquely  upwards  and  inwards,  in  obedience  botb  to  tbe  centrifu- 
gal force  and  the  power  of  gravitation,  acting  at  right  angles  to 
each  other.  That  light  is  the  chief  cause  of  the  upward  direction 
of  the  stem,  while  it  is  avoided  by  the  roots,  appears  from  a  recent 
experiment  by  Professor  Schultz,  of  Berlin  ;  who  reversed  the  nat- 
ural condition,  by  causing  seeds  to  germinate  in  Moss,  so  arranged 
that  the  only  light  they  could  receive  was  reflected  from  a  mirror, 
which  threw  the  solar  rays  upon  them  directly  from  below ;  in 
which  case  he  found  that  their  roots  were  sent  upward  into  the 
Moss,  contrary  to  the  ordinary  direction,  and  their  stems  down- 
ward towards  the  light. 

650.  The  Mistletoe  obeys  the  attraction  of  the  trunk  or  branch 
upon  which  it  is  parasitic  (134),  just  as  ordinary  plants  obey  the 
attraction  of  the  earth ;  its  roots  penetrating  towards  the  centre, 
while  the  stems  grow  perpendicular  to  the  surface  of  the  branch, 
and  are  therefore  placed  in  various  positions  as  respects  the  earth. 
When  the  germinating  seeds  of  the  Mistletoe  were  glued  to  the 
surface  of  a  cannon-ball,  all  the  radicles  were  found  to  be  directed 
toward  its  centre.  A  well-devised  experiment  made  by  Dutrochet 
goes  to  show,  that  the  direction  of  the  radicle  to  the  adjacent  body 
(and  consequently  of  the  germinating  root  generally  towards  the 
earth's  centre)  is  not  the  result  of  the  immediate  attraction  of  the 
adjacent  body,  or  of  the  earth,  but  is  a  spontaneous  movement  due 
to  some  internal,  vital  cause,  put  inj action  by  the  exterior  influ- 
ence. He  mounted  the  seed  of  a  Mistletoe  upon  one  extremity  of 
a  very  delicately  balanced  needle,  which  would  turn  with  the 
slightest  force,  and  placed  it  at  the  distance  of  half  a  line  from  the 
surface  of  a  large  cannon-ball.  In  germination  the  radicle  directed 
its  point  to  the  ball,  and  soon  came  into  contact  with  the  surface  ; 
but  that  end  of  the  needle  had  not  moved  in  the  slightest  degree 
towards  the  ball,  as  it  would  have  done  from  a  mere  exterior  at- 
traction. 

651.  When  the  stem  has  emerged  from  the  earth,  it  tends  to 
expose  itself  as  much  as  possible  to  the  light,  the  growing  parts 
always  turning  towards  the  side  most  strongly  illuminated  ;  as  is 
observed  when  a  plant  is  placed  in  an  apartment  lighted  from  a 
single  aperture.  This  is  mechanically  accounted  for  by  De  Can- 
dolle,  on  the  supposition,  that,  as  the  side  upon  which  the  light 
strikes  will  fix  most  carbon  by  the  decomposition  of  carbonic  acid, 
so  its  tissue  will  become  more  solid  than  the  shady  side,  and  there- 

29* 


342  SPONTANEOUS    MOVEMENTS    IN    PLANTS. 

fore  elongate  less  rapidly ;  and  the  stem  or  branch  will  conse- 
quently bend  towards  the  light.  But  when  the  light  is  equally  dif- 
fused around  a  plant,  the  decomposition  of  carbonic  acid  will  take 
place  uniformly  on  all  sides,  and  the  perpendicular  direction  natu- 
rally be  maintained.  The  same  law  would  regulate  the  disposition 
of  branches,  which  are  invariably  so  arranged  as  to  have  the  great- 
est possible  exposure  to  the  light ;  the  uppermost  branches  of  a 
tree  growing  nearly  erect,  those  beneath  them  extending  more 
horizontally  until  they  reach  beyond  their  shade,  when  they  curve 
upwards  (unless  too  slender  to  support  their  own  weight,  as  in  the 
Weeping  Willow),  and  the  lower  being  still  more  divergent,  or  even 
turned  downwards,  when  the  foliage  is  dense.  The  divergence  of 
the  branchlets  takes  place  in  the  same  manner.  This  effect,  how- 
ever, is  confined  to  the  green  parts  of  plants,  which  alone  decom- 
pose carbonic  acid  under  the  influence  of  light  (344).  The  direc- 
tion of  old  branches,  where  the  surface  has  lost  its  green  color,  is 
no  longer  affected  by  the  light ;  and  those  which  creep  under 
ground  beyond  its  influence  (173),  and  have  the  white  color  and 
much  the  external  appearance  of  roots,  show  little  upward  ten- 
dency so  long  as  they  remain  in  this  situation  ;  but  whenever 
their  extremities  are  exposed  to  the  light,  they  first  acquire  a 
green  hue  by  the  formation  of  chlorophyll,  and  then  tend  to  as- 
sume a  vertical  direction. 

652.  In  leaves,  it  is  the  deeper-colored  surface  that  is  always 
presented  to  the  light.  But  the  turning  of  this  surface  towards  the 
light  cannot  be  explained  as  a  mere  physical  effect  of  that  agent 
upon  the  leaf.  A  leaf  cut  from  its  stalk,  attached  to  a  hair,  and 
plunged  by  a  bit  of  lead  in  a  glass  vessel  filled  with  water,  when 
exposed  in  a  window,  will  perform  its  functions  of  digestion  as  well 
as  ever,  but  it  will  not  turn  its  upper  surface  towards  the  light. 
The  light  can  produce  this  motion  only  by  its  influence  on  some 
power  inherent  in  the  vegetable  itself. 

653.  Still  less  will  purely  physical  explanations  account  for  the 
reaching  forth  of  tendrils,  or  the  twining  of  those  stems  which  act 
like  tendrils ;  in  which  the  green  parts  turn  from  the  light,  instead 
of  towards  it.  We  pass  to  more  obvious  cases  of  spontaneous 
movements.  One  of  the  most  general  of  these  is  what  was  termed 
by  Linnseus 

654.  The  Sleep  of  Plants,  namely,  the  peculiar  position  which  the 
leaves  of  many  plants  assume,  either  by  drooping,  or  by  the  fold- 


THE    SLEEP    OF    PLANTS.  343 

ing  together  of  their  leaflets,  as  if  in  repose,  when  the  stimulus 
of  light  is  removed.  This  is  well  seen  in  the  foliage  of  the 
liocust  and  of  most  Leguminous  plants,  and  in  those  of  Oxalis,  or 
Wood-Sorrel.  It  is  most  striking  in  the  leaflets  of  compound 
leaves.  Their  nocturnal  position  is  various  in  different  species, 
but  uniform  in  the  same  species,  showing  that  the  phenomenon  is 
not  mechanical.  Nor  is  it  a  passive  state,  for,  instead  of  drooping 
as  if  by  their  own  weight,  the  leaflets  are  more  commonly  turned 
upwards  or  forwards,  contrary  to  the  position  into  which  they 
would  fall  from  their  own  weight.  De  Candolle  found  that  most 
plants  could  be  made  to  acknowledge  an  artificial  day  and  night, 
by  keeping  them  in  darkness  during  the  day,  and  by  illuminating 
them  with  candles  at  night.  The  sensibility  to  light  appears  to 
reside  in  the  petiole,  and  not  in  the  blade  of  the  leaf  or  leaflet :  for 
these  movements  are  similarly  executed,  when  nearly  the  whole 
surface  of  the  latter  is  cut  away. 

655.  The  leaves  of  the  blossom  also  assume  various  positions, 
according  to  the  intensity  and  duration  of  the  light.  Many  expand 
their  blossoms  in  the  morning  and  close  them  towards  evening, 
never  to  be  opened  again,  as  those  of  Cistus  and  of  many  Portula- 
caceous  plants ;  while  others,  like  the  Crocus,  close  when  the  sun 
is  withdrawn,  but  expand  again  the  following  morning.  On  the 
other  hand,  the  Evening  Primrose,  Silene  noctiflora,  &c.,  unfold 
their  petals  at  twilight,  and  close  at  sunrise.  The  White  Water- 
Lily  (Nympheea)  expands  in  the  full  light  of  day,  but  uniformly 
closes  near  the  middle  of  the  afternoon,  and  is  then  usually  with- 
drawn beneath  the  surface  of  the  water.  The  Morning  Glory 
opens  at  the  dawn ;  the  Lettuce  and  most  Cichoraceous  plants,  a 
few  hours  later;  the  Mirabilis,  or  Four-o'clock  plant,  nearly  at 
that  hour  in  the  afternoon,  &c.  Berthelot  mentions  an  Acacia  at 
Teneriffe,  whose  leaflets  regularly  close  at  sunset  and  unfold  at 
sunrise,  while  its  flowers  close  at  sunrise  and  unfold  at  sunset.* 


*  The  odors  of  flowers,  also,  are  sometimes  given  off  continually,  as  in  the 
Orange  and  the  Violet,  or  else  they  nearly  lose  their  fragrance  during  the  heat 
of  mid-day,  as  in  most  cases  ;  while  others,  such  as  Pelargonium  triste,  Hes- 
peris  tristis,  and  most  dingy  flowers,  which  are  almost  scentless  during  the 
day,  exhale  a  powerful  fragrance  at  night.  The  night-flowering  Cereus  gran- 
diflorus  emits  its  powerful  fragrance  at  intervals ;  sudden  emanations  of  odor 
being  given  off  about  every  quarter  of  an  hour,  during  the  brief  period  of  the 
expansion  of  the  flower. 


344  SPONTANEOUS    MOVEMENTS    IN    PLANTS. 

656.  Movements  from  Irritation.  The  leaflets  of  numerous  Legu- 
minous plants,  especially  of  the  Mimosa  tribe,  when  roughly 
touched,  assume  their  peculiar  nocturnal  position  by  a  visible  and 
sometimes  a  rapid  movement.  The  Sensitive  Plant  of  the  gardens 
(Mimosa  pudica)  is  a  familiar  instance  of  the  kind  :  but  it  does  not 
greatly  exceed  the  Mimosa  strigillosa  and  the  Schrankia  of  the 
Southern  States,  where  the  leaflets  promptly  fold  up  when  brushed 
with  the  hand.  The  most  remarkable  instance  of  the  kind,  how- 
ever, is  presented  by  another  native  plant  of  the  United  States,  the 
Dionsea  muscipula,  or  Venus's  Fly-trap  (Fig.  228) ;  in  which  the 
touch  even  of  an  insect,  alighting  upon  the  upper  surface  of  the 
outspread  lamina,  causes  its  sides  to  close  suddenly,  the  strong 
bristles  of  the  marginal  fringe  crossing  each  other  like  the  teeth  of 
a  steel-trap,  and  the  two  surfaces  pressing  together  with  consid- 
erable force,  so  as  to  retain,  if  not  to  destroy,  the  intruder,  whose 
struggles  only  increase  the  pressure  which  this  animated  trap 
exerts.  This  most  extraordinary  plant  grows  abundantly  in  the 
damp  sandy  savannas  in  the  neighbourhood  of  the  Cape  Fear 
River,  especially  from  Wilmington  to  Fayetteville,  North  Car- 
olina, where  it  is  exceedingly  abundant ;  but  it  is  not  elsewhere 
found. 

657.  A  familiar,  although  less  striking,  instance  of  the  same  kind 
is  seen  in  the  stamens  of  the  common  Barberry,  which  are  so  ex- 
citable, that  the  filament  approaches  the  pistil  with  a  sudden  jerk, 
when  touched  with  a  point,  or  bruvshed  by  an  insect,  near  the  base 
On  the  inner  side.  The  object  of  this  motion  seems  plainly  to  be 
the  dislodgement  of  the  pollen  from  the  cells  of  the  anther,  and  its 
projection  upon  the  stigma.  But  in  the  Dionsea  it  is  difficult  to 
conceive  what  end  is  subserved  as  to  the  plant  by  the  capture  of 
insects. 

658.  In  a  species  of  Stylidium  of  New  Holland,  not  uncommon 
in  conservatories,  the  column,  consisting  of  the  united  stamens  and 
styles,  is  bent  over  to  one  side  of  the  corolla  ;  but  if  slightly  irritated, 
it  instantly  springs  over  to  the  opposite  side  of  the  flower.  Some 
other  movements,  which  have  been  likened  to  these,  are  entirely 
mechanical  in  their  nature ;  as  that  of  Kalmia,  or  Sheep  Laurel, 
where  the  ten  anthers  are  in  the  bud  received  into  as  many  pouches 
of  the  monopetalous  corolla,  and  being  retained  by  a  glutinous  ex- 
udation, are  carried  outwards  and  downwards  when  the  corolla 
expands.     In  this  way  the  slender  filaments  are  strongly  recurved, 


AUTOMATIC    MOVEMENTS.  345 

like  so  many  springs,  until  the  anthers  open,  and  the  pollen  absorbs 
the  glutinous  matter  that  confines  them,  when  they  fly  upwards 
elastically,  throwing  the  pollen  in  the  direction  of  the  stigma.  The 
bursting  of  the  fruit  of  the  Squirting  Cucumber  (Momordica  Elate- 
rium),  and  the  elastic  dehiscence  of  the  Balsam,  or  Touch-me- 
not  (Tmpatiens),  are  also  due  to  mechanical  or  endosmotic  (37) 
causes ;  and  therefore  are  not  to  be  adduced  as  instances  of  vege- 
table irritability. 

659.  Automatic  Movements.  A  few  plants  are  known  which  exe- 
cute brisk  and  repeated  movements  irrespective  of  extraneous 
excitation,  and  which,  indeed,  are  arrested  by  the  touch.  An  in- 
stance of  such  spontaneous  and  continued  motion,  of  the  most  re- 
markable kind,  is  furnished  by  the  trifoliolate  leaves  of  Desmodium 
gyrans,  an  East  Indian  Leguminous  plant.  The  terminal  leaflet 
does  not  move,  except  to  change  from  the  diurnal  to  the  nocturnal 
position,  and  the  contrary  ;  but  the  lateral  ones  are  continually  ris- 
ing and  falling,  both  day  and  night,  by  a  succession  of  little  jerks, 
like  the  second-hand  of  a  time-keeper ;  the  one  rising  while  the 
other  falls.  Exposure  to  cold,  or  cold  water  poured  upon  the 
plant,  stops  the  motion,  which  is  immediately  renewed  by  warmth. 
In  several  tropical  Orchideous  plants,  and  especially  in  a  species  of 
Megaclinium,  one  of  the  petals  executes  similar  and  perfectly  spon- 
taneous automatic  movements. 

660.  Free  Movements  of  the  Spores  of  Algse.    The  spores  of  many 

of  the  lower  Algse  are  now  known  to  exhibit  a  peculiar  active  state 
at  the  time  of  their  discharge  from  the  parent  cell,  when,  for  some 
moments,  or  usually  for  several  hours,  they  behave  like  infusory 
animals,  executing  free,  and  to  all  appearance  spontaneous,  move- 
ments in  the  water,  until  they  are  about  to  germinate.  This  singu- 
lar movement  was  first  detected,  many  years  ago,  in  Vaucheria.  In 
Fig.  71,  (p.  67,)  we  see  the  manner  in  which  the  spore  is  formed ; 
and  in  Fig.  72,  the  mode  in  which  it  is  discharged :  also,  on  a 
larger  scale,  in  Fig.  467.  It  at  once  begins  to  move  freely  in  the 
water,  and  continues  to  do  so  for  some  hours,  when  it  fixes  itself 
and  begins  to  grow  (Fig.  469).  Its  movements,  moreover,  may  be 
enfeebled  or  arrested  by  the  application  of  a  weak  solution  of  opi- 
um or  of  chloroform.  Through  these  means  it  has  been  ascer- 
tained that  they  are  caused  by  the  vibrations  of  minute  cilia  which 
cover  the  surface,  which  are  rendered  visible  by  thus  enfeebling 
their  rapid  movement,  and  which  exhibit  the  closest  resemblance 


SPONTANEOUS    MOVEMENTS    IN    PLANTS. 


to  the  vibratile  cilia  of  animals,  especially  those  of  the  polygastric 

animalcules  !    In  Conferva 

vesicata,  the  vibratile  cilia 

are  found  to  occupy  one 

end  of  the  spore  (Fig.  475). 

In  other  species,  they  are 

likewise  restricted  to  some 

one  part  of  the  surface,  but 

are  only  two  or  three  in 

number. 

661.  In  Oscillaria  (Fig. 
66,  p.  66)  the  fully  devel- 
oped plant  exhibits  occa- 
sional writhing  movements, 
so  well  marked  that  the 
vegetable  character  of  the 
genus  was  once  question- 
ed. The  Closteria  (Fig. 
77)  and  other  minute  Des- 
midiaceous  plants  exhibit 
well-marked  spontaneous 
movements  of  translation  from  time  to  time :  and  the  nearly  allied 
Diatomacese  —  the  lowest  and  most  ambiguous  of  plants  —  were 
long  referred  to  the  animal  kingdom,  on  account  of  the  energetic 
motions  they  exhibit.  The  lowest  tribe  of  plants,  in  this  as  in 
other  respects,  makes  the  closest  approach  to  the  lowest  tribes  of 
animals. 

662.  Not  only,  therefore,  do  many,  if  not  all,  plants  manifest 
sensitiveness  to  external  agents,  and  more  or  less  decided,  though 
slow,  movements ;  but  many  species  of  the  higher  grades  exhibit 
certain  vivid  motions,  either  spontaneous  or  automatic,  or  in  conse- . 
quence  of  extraneous  irritation ;  while  the  lowest  tribes  of  aquatic 
plants,  as  they  diminish  in  size  and  in  complexity  of  organization, 
habitually  exhibit,  at  some  period  of  their  lives  at  least,  varied 


FIG.  467.  Fruiting  end  of  a  plant  of  Vaucheria  geminata  (after  Thuret) ;  one  of  the  branches 
still  containing  its  spore.  463.  Moving  spore  just  escaped  from  the  apex  of  the  other  branch; 
the  ciliary  apparatus  seen  over  the  whole  surface.     469.  Spore  in  germination. 

FIG.  470-473.  Successive  steps  in  the  germination  of  Conferva  vesicata.  474.  The  plant 
developed  into  a  series  of  cells,  four  of  which  display  the  successive  steps  in  the  formation  of  a 
spore.  475.  The  locomotive  spore  with  its  vibratile  cilia  (copied  from  Thuret).  When  the 
movement  ceases,  and  it  begins  to  germinate,  it  appears  as  in  470. 


DISTINCTION    BETWEEN    PLANTS    AND   ANIMALS.  347 

spontaneous  movements  which  we  are  unable  to  distinguish  in 
character  from  those  of  the  lowest  animals  (16),  at  least  from  those 
made  by  cilia. 

663.  When  we  consider  that  the  excitability  of  sensitive  plants 
is  often  transmitted,  as  if  by  a  sort  of  sympathy,  from  one  part  to 
another  ;  that  it  is  soon  exhausted  by  repeated  excitation  (as  is 
certainly  the  case  in  Dionsea,  the  Sensitive  Plant,  &c.),  and  is  only 
renewed  after  a  period  of  repose  ;  that  all  plants  require  a  season 
of  repose  ;  that  they  evolve  heat  under  special  circumstances  (372 
-374)  ;  that,  as  if  by  a  kind  of  instinct,  the  various  organs  of  the 
vegetable  assume  the  positions  or  the  directions  most  favorable  to 
the  proper  exercise  of  their  functions  and  the  supply  of  their  wants, 
to  this  end  surmounting  intervening  obstacles  ;  —  when  we  consid- 
er in  this  connection  the  still  more  striking  cases  of  spontaneous 
motion  that  the  lower  Algse  exhibit,  and  that  all  these  motions  are 
arrested  by  narcotics,  or  other  poisons,  —  the  narcotic  and  acrid 
poisons  even  producing  effects  upon  vegetables  respectively  analo- 
gous to  their  different  effects  upon  the  animal  economy ;  —  we  can 
hardly  avoid  attributing  to  plants  a  sensibility  and  a  power  of 
"  making  movements  tending  to  a  determinate  end,"  not  different 
in  nature,  so  far  as  we  know,  from  those  of  the  lowest  animals. 
Probably  the  vitality  is  essentially  the  same  in  the  two  kingdoms  ; 
and  to  this,  faculties  and  attributes  are  superadded  in  the  lower 
animals,  some  of  which  are  here  and  there  not  indistinctly  fore- 
shadowed in  plants. 

664.  Finally,  if  called  upon  to  define  a  plant,  or  draw  the  line 
between  the  animal  and  the  vegetable  kingdoms,^we  can  only  say, 
—  1.  That  plants  alone,  under  the  solar  influence,  create  organic 
matter  from  inorganic  materials,  and  alone  live,  or  are  capable  of 
living,  by  direct  aggression  upon  the  mineral  world.  Consequent- 
ly, they  alone  decompose  carbonic  acid,  and  render  free  oxygen 
gas  to  the  atmosphere  (Chap.  VI.)  :  the  action  of  animals  upon  the 
air  is  uniformly  and  continually  the  reverse.  2.  In  its  structure, 
a  plant  may  be  reduced  to  a  single  simple  vesicle  of  cellular  tissue 
(94),  containing  chlorophyll,  or  its  equivalent.  But  a  developed 
animal  of  the  very  lowest  grade  has  a  more  complex  structure  : 
from  the  necessity  of  the  case  it  possesses  a  mouth  and  a  stomach. 
Indeed,  we  have  reason  to  believe  that  the  polygastric  animalcules 
are  considerably  complicated  in  structure.  3.  As  to  chemical 
composition,  the  tissue  of  plants,  or  the  material  of  which  the  fab- 


348  DISTINCTION    BETWEEN    PLANTS    AND   ANIMALS. 

ric  is  constructed,  is  a  neutral  ternary  product  (27,  347),  com- 
posed of  carbon,  hydrogen,  and  oxygen.  Although  the  plant  ne- 
cessarily contains  and  produces  the  quaternary  organic  products, 
these  do  not  enter  into  the  composition  of  its  permanent  fabric. 
The  animal  tissue,  on  the  contrary,  is  directly  composed  of  neutral 
quaternary  products,  consisting  of  carbon,  hydrogen,  oxygen,  and 
nitrogen.  Although  such  distinctions  as  these  are,  in  all  probabil- 
ity, absolute,  yet  it  is  often  difficult,  and  frequently,  perhaps,  im- 
possible, to  apply  them  to  the  actual  discrimination  of  the  lower 
plants  from  the  lower  animals. 


PART    II. 
SYSTEMATIC     BOTANY. 


665.  We  have  now  to  contemplate  the  vegetable  creation  from 
a  different  point  of  view.  In  studying  the  structure  and  physiol- 
ogy of  plants,  we  have  been  struck  with  the  countless  varieties 
which  they  present,  —  the  almost  infinite  number  of  particular 
modes  or  forms  in  which  the  general  plan  of  vegetation  has  been 
worked  out,  as  it  were,  in  detail.  The  vegetable  kingdom,  that  is, 
vegetation  taken  as  a  great  whole,  presents  to  our  view  an  im- 
mense number  of  different  kinds  or  sorts  of  plants,  more  or  less 
resembling  each  other,  more  or  less  nearly  related  to  each  other. 
It  is  the  object  of  Systematic  Botany  to  consider  them  in  respect  to 
these  resemblances  and  differences,  —  to  contemplate  the  relations 
which  the  individual  members  of  the  great  whole  sustain  to  each 
other  (5,  6).  In  this  view,  the  botanist  classifies  them,  so  as  to 
exhibit  their  relationships,  or  points  of  resemblance,  arranges  them 
in  an  orderly  manner,  designates  them  by  proper  names,  and  dis- 
tinguishes them  by  clear  and  precise  descriptions  ;  so  that  the  name 
and  place  in  the  system,  the  known  properties,  and  the  whole  his- 
tory of  any  given  plant,  may  be  readily  and  surely  obtained  by  the 
learner. 


CHAPTER    I. 

OF    CLASSIFICATION    AND    ITS    PRINCIPLES. 

666.  ludiTiduals.     The  vegetables  with  which  the  earth  is  adorn- 
ed are  presented  to  our  view  as  Individuals  only,  more  or  less 
30 


350  CLASSIFICATION. 

resembling,  or  differing  from,  each  other.  Among  these,  some 
are  so  essentially  alike,  that  we  involuntarily  apply  to  them  the 
same  name.  A  field  of  Wheat  is  filled  with  similar  individuals, 
which  we  can  separate^  but  cannot  distinguish.  Or,  although  it 
be  possible  to  distinguish  separate  individuals,  from  any  peculiarity 
of  size,  &;c.,  we  still  inevitably  associate  them,  as  being  much 
more  like  each  other  than  like  any  surrounding  forms,  —  so  like, 
that  we  view  the  difference  as  an  accidental  circumstance.  Fur- 
thermore, the  Wheat  tillers^  that  is,  branches  from  the  ground, 
and  shoots  forth  a  number  of  stalks  from  the  same  root,  —  stalks 
which  are  separable,  or  separate  spontaneously,  from  the  primary 
one.  So,  also,  the  branches  of  trees,  which  may  grow  indefinitely 
as  a  part  of  an  original  tree  (148),  become,  when  detached  and 
planted  by  themselves  in  the  soil,  independent,  but  perfectly  similar 
individuals  (167,  229).  Probably  all  the  Weeping  W^illows,  or 
Lombardy  Poplars,  of  this  country  have  sprung  in  this  way  from  a 
single  shoot.  The  grain  of  wheat,  also,  will  reproduce  similar 
individuals,  and  none  other.  Now,  upon  such  universal  and  inev- 
itable conceptions  as  these  rests  the  idea  of 

667.  Species.  We  mentally  assemble,  under  this  name,  those 
individuals  which  we  observe  or  judge  to  have  arisen  from  one 
parent  stock,  or  which,  although  met  with  widely  dissociated,  re- 
semble each  other  so  closely  that  we  infer  them  to  have  had  a 
common  parentage.  A  Species  we  have  already  defined  (14)  to 
be,  abstractly,  the  type  or  original  of  each  sort  of  plant,  or  animal, 
thus  represented  in  time  by  a  perennial  succession  of  like  individ- 
uals, or,  concretely,  the  sum  of  such  individuals.  It  embraces  all 
those  individuals  which,  slightly  differing,  perhaps,  in  size,  color,  or 
such  unimportant  respects,  resemble  each  other  more  nearly  than 
they  resemble  any  other  plants,  so  that  we  infer  them  to  have 
sprung  from  a  common  original  stock,  and  which  preserve  their 
characters  unchanged  when  propagated  by  seed.  All  classifica- 
tion and  system  in  natural  history  rest  upon  the  fundamental  idea 
of  the  original  creation  of  certain  forms,  which  have  naturally  been 
perpetuated  unchanged,  or  with  such  changes  only  as  we  may 
conceive  or  prove  to  have  arisen  from  varying  physical  influences, 
accidental  circumstances,  or  from  cultivation.  Whether  the  origi- 
nal stock  consisted  of  one  individual  or  pair,  or  of  numerous  indi- 
viduals, is  not  material  to  the  view.  (On  the  latter  supposition, 
however,  we  can  readily  perceive  that  certain  varieties  or  races 
may  have  been  aboriginal.) 


INDIVIDUALS,    SPECIES,    AND    VARIETIES.  351 

668.  Yarieties.  This  fraternal  resemblance,  or  specific  identity, 
however,  is  not  incompatible  with  individual  peculiarity.  If  two 
seeds  from  the  same  pod  are  sown  in  different  soils,  and  submitted 
to  different  conditions  as  respects  heat,  light,  and  moisture,  the 
plants  that  spring  from  them  will  show  marks  of  this  different 
treatment  in  their  appearance.  Such  differences  are  continually 
arising  in  the  natural  course  of  things.  To  produce  and  increase, 
and  by  artificial  management  to  perpetuate,  differences  of  this  sort, 
forms  an  important  part  of  the  art  of  cultivation.  These  minor  de- 
viations, not  incompatible  with  the  idea  of  a  common  origin,  con- 
stitute Varieties.  Whenever  the  conditions  that  give  rise  to  vari- 
eties are  carried  to  excess,  these  individuals  fail  to  fructify,  or 
perish.  When  the  conditions  vary  less  widely  from  those  most 
propitious  to  the  constitution  of  the  particular  species,  a  few  years 
or  a  few  generations  may  suffice  to  bring  the  variety  back  to  the 
original  form.  In  either  case,  the  variation  is  transient.  It  must 
either  return  to  the  common  character  of  the  species,  or  perish. 
A  certain  flexibility  is  allowable ;  but  accidental  and  individual 
variations  tend  to  disappear  with  the  causes  which  originate  them, 
or  are  destroyed  by  the  continued  operation  of  those  causes. 

669.  To  this  there  is  one  class  of  exceptions,  which  is  exceed- 
ingly common  in  domesticated  plants ;  where  the  habit,  once  es- 
tablished, outlasts  the  cause,  and  continues  throughout  the  life  of 
the  individual.  The  new  buds  and  branches  partake  of  the  pecu- 
liarity, and  the  variety  may  consequently  be  perpetuated  by  cut- 
tings, grafts,  &c. ;  as  is  the  case  with  our  Apples,  Pears,  &c.  But 
this  tendency  does  not  inhere  in  the  seed. 

670.  Races.  There  is  still  another  and  more  strongly  marked 
kind  of  variety,  —  though  unknown,  perhaps,  in  a  perfectly  wild 
state,  —  in  which  the  characteristics  are  transmissible  by  seed. 
Particular  varieties  of  Peas,  Radishes,  Lettuce,  &c.,  are  thus  per- 
petuated in  our  gardens  ;  and  in  agriculture,  various  sorts  of  grain 
have  thus  been  preserved  from  time  immemorial.  They  have  re- 
ceived the  name  of  Races.  It  is  not  known  how  they  originate. 
They  start  up,  as  it  were,  accidentally,  from  time  to  time,  in  culti- 
vated plants.  The  cultivator  selects  the  most  promising  sorts,  or 
"  sports,"  for  preservation,  leaving  the  others  to  their  fate.  By 
peculiar  care  he  developes  and  strengthens  the  tendency  to  become 
hereditary,  and  renders  it  paramount  (under  the  circumstances  and 
conditions  of  cultivation)  to  that  stronger  natural  tendency  to  re- 


352  CLASSIFICATION. 

version  to  the  primitive  type,  and  so  secures  his  particular  end. 
The  races  of  Corn,  Wheat,  &c.,  which  now  preserve  their  charac- 
ter unchanged,  have  become  fixed  by  centuries  of  domestication. 
Even  these,  at  times,  manifest  an  unequivocal  disposition  to  return 
to  their  aboriginal  state.  Were  cultivation  to  cease,  they  would  all 
speedily  disappear ;  the  greater  part,  perhaps,  would  perish  out- 
right ;  the  remainder  would  revert,  in  a  few  generations  of  sponta- 
neous growth,  to  the  character  of  the  primitive  stock. 

671.  Hybrids  or  Cross-breeds.  Variations  of  a  still  different  class 
are  artificially,  and  sometimes  spontaneously,  produced,  by  fertiliz- 
ing the  ovary  of  one  plant  with  the  pollen  of  a  nearly  allied  spe- 
cies ;  from  which  arise  what  are  called  Cross-hreeds,  or  Hybrids. 
Crosses  between  different  species,  however,  are  almost  always  in- 
capable of  producing  fertile  seed,  and  therefore  are  not  perpetu- 
ated in  nature  :  those  between  distinct  varieties  of  the  same  spe- 
cies are  usually  fertile,  and  give  rise  to  new  sets  of  varieties  (also 
termed  Races)^  in  which  the  particular  qualities  of  their  immediate 
parents  are  variously  modified  or  blended  ;  but  which,  by  a  contin- 
uation of  the  same  influences,  revert  to  one  or  the  other  parent 
stock. 

672.  Genera.  If  but  a  moderate  number  of  species  were  known, 
no  system  of  generalizing,  or  arranging  them  in  groups,  would  be 
necessary  for  ordinary  purposes ;  though  a  consideration  of  the 
various  degrees  of  resemblance  between  different  species  could  not 
fail  to  suggest  some  form  of  generalization,  like  that  which  the 
great  number  of  species  early  rendered  necessary.  The  first  step 
in  proper  classification,  the  bringing  together  of  species  into  kinds, 
according  as  they  are  seen  to  resemble  each  other,  is  almost  as 
natural  and  inevitable  an  operation  of  the  mind,  as  is  the  idea  of 
species  involuntarily  deduced  from  the  assemblage  of  like  individ- 
uals. The  generic  association,  however,  implies  only  resemblance, 
or  similarity  of  kind,  not  identity  of  origin.  A  Genus,  therefore, 
is  an  assemblage  of  nearly  related  species,  formed  after  the  same 
pattern,  and  therefore  agreeing  with  one  another  in  general  struc- 
ture and  appearance.  Thus,  the  wild  Swamp  Rose,  the  Sweet- 
brier,  the  Dog  Rose,  French  Rose,  Cinnamon  Rose,  and  others, 
constitute  the  universally  recognized  genus  Rosa  ;  the  various  spe- 
cies of  Raspberry  and  Blackberry  compose  the  genus  Rubus  ;  the 
Apple,  Pear,  &c.,  form  the  genus  called  by  botanists  Pyrus  :  so 
the  different  Oaks,  Willows,  Poplars,  Birches,  &c.,  form  as  many 


GENERA  AND  ORDERS  OR  FAMILIES.  353 

separate  genera.  The  languages  of  the  most  barbarous  people 
show  that  they  have  formed  such  associations.  Naturalists  merely 
give  to  these  generalizations  a  greater  degree  of  precision,  and 
endeavour  to  indicate  what  the  points  of  common  agreement  are. 
A  single  species,  also,  may  be  deemed  to  constitute  a  genus,  when 
its  peculiarities  are  equivalent  in  degree  to  those  which  charac- 
terize other  genera,  —  a  case  which  often  occurs.  If  only  one 
species  of  Oak  were  known,  the  Oak  genus  would  have  been  as 
explicitly  recognized  as  it  is  now  that  the  species  amount  to  two 
hundred  ;  it  would  have  been  equally  distinguished  by  its  acorn 
and  cup  from  the  Chestnut,  Beech,  Hazel,  &c.  A  genus,  then,  is 
a  group  of  species  which  present  the  same  particular  plan,  and 
whose  mutual  resemblance  is  greater  than  that  of  any  one  of  them 
to  any  other  plant. 

673.  When  two  or  more  species  of  a  genus  resemble  each  other 
in  particular  points  more  nearly  than  they  do  the  other  species, 
intermediate  sections  are  often  recognized  ;  which,  when  marked 
by  characters  of  considerable  importance,  receive  the  title  of 
Subgenera. 

674.  Orders  or  Families.  If  the  genera  were  few,  there  would  be 
little  necessity  for  higher  generalizations ;  although  one  could  not 
but  remark  that  the  Oaks,  Chestnuts,  Beeches,  and  Hazels  have  a 
strong  common  resemblance,  or  family  likeness  ;  and  that  they  are 
more  unlike  Birches  and  Alders,  or  Walnuts  and  Hickories ;  that 
they  are  still  more  unlike  Maples  or  Ashes,  and  have  yet  fewer 
points  in  common  with  Pines  and  Firs.  But,  since  the  100,000 
species  of  known  plants  are  distributed  among  nearly  8,000  gen- 
era, it  is  necessary  to  consider  these  family  resemblances,  for  the 
purpose  of  grouping  the  genera  into  still  higher,  and  therefore  few- 
er, groups ;  just  as  genera  are  formed  by  the  reunion  of  related 
species.  The  groups  thus  established  are  termed  Families,  or 
Orders  (names  which  are  for  the  most  part  used  interchangeably 
in  botany).  Thus,  the  Rose,  the  Raspberry  and  Blackberry,  with 
the  Strawberry  the  Apple,  the  Thorn,  the  Plum  and  Cherry,  &c., 
all  agreeing  in  their  general  plan  of  structure,  are  brought  together 
into  one  order  or  family,  and  termed  RosacecB ;  that  is,  Rosaceous 
or  Rose-like  plants. 

675.  But,  viewed  subordinately,  the  Plum  and  Cherry  are  evi- 
dently more  nearly  akin  than  the  Cherry  and  Apple,  &c. ;  and  so 
the  Raspberry,  Blackberry,  and  Strawberry  on  one  hand,  and  the 

30* 


354  CLASSIFICATION. 

Apple  and  Thorn  on  the  other,  exhibit  a  closer  relationship  than 
that  which  connects  them  all  in  one  common  group.  Hence  they 
are  respectively  distinguished  into  groups  of  a  rank  intermediate 
between  genera  and  orders,  which  are  variously  termed  Subor- 
ders, or  Tribes.* 

676.  Classes  are  groups  of  orders,  associated  in  a  similar  manner 
from  some  higher  point  of  view.  Subclasses  bear  the  same  rela- 
lion  to  classes  that  suborders  do  to  orders. 

677.  By  this  regular  subordination  of  groups,  the  various  degre'es 
of  relationship  among  plants  may  be  expressed  ;  and  upon  this  Sys- 
tematic Botany  essentially  depends.  Only  four  of  these  divisions 
are  universally  employed,  namely.  Classes,  Orders,  Genera,  and 
Species :  these  are  common  to  all  methods  of  classification,  both 
in  the  animal  and  vegetable  kingdoms,  and  are  always  arranged 
in  the  same  sequence.  But  a  more  elaborate  analysis  is  often 
requisite,  on  account  of  the  large  number  of  objects  to  be  arranged, 
and  the  various  degrees  of  aflinity  to  be  expressed  ;  when  the  ad- 
ditional members,  and  if  need  be  several  others,  are  introduced  ; 
as  in  the  following  descending  series,  beginning  with  the  primary 
division  of  natural  objects  into  kingdoms,  and  indicating  by  small 
capitals  those  of  fundamental  importance  and  universal  use. 

Kingdoms, 
Series, 

Classes, 

Subclasses, 

Orders,  or  Families,   . 
Suborders, 
Tribes, 

Subtribes, 
Genera, 

Subgenera, 
Species, 

Varieties. 

678.  Characters.     An  enumeration  of  the  distinguishing  marks, 

*  When  the  groups  which  an  order  embraces  are  distinguished  by  charac- 
ters of  nearly  equal  value  with  those  commonly  employed  for  orders  them- 
selves, they  are  termed  Suborders.  Thus,  the  Plum,  Cherry,  Apricot, 
Peach,  &c.,  form  one  suborder  of  Rosaceae;  the  Raspberry,  Blackberry, 
Strawberry,  Cinquefoil,  with  the  Rose  and  other  genera,  constitute  another 
suborder ;  and  the  Apple,  the  duince,  Thorn,  &c.,  a  third.     The  name  of 


SUBORDINATION  OF  GROUPS  I  CHARACTERS.         355 

or  points  of  difference  between  one  class  or  order,  &c.,  and  the 
Others,  is  ternned  its  character.  The  characters  of  the  classes,  and 
other  prinnary  divisions,  embrace  only  those  important  points  of 
structure  upon  which  they  are  constituted :  the  ordinal  character 
describes  the  general  structure  of  the  iticluded  plants,  especially  of 
their  flowers  and  fruit :  the  generic  character  points  out  the  partic- 
ular modifications  of  the  ordinal  structure  in  a  given  genus ;  and 
the  specific  character^  those  less  important  modifications  of  form, 
relative  size  of  parts,  color,  &c.,  which  serve  to  distinguish  kindred 
species.  A  complete  system  of  Botany  will  therefore  comprise  a 
methodical  distribution  of  plants  according  to  their  organization, 
with  their  characters  arranged  in  proper  subordination  ;  so  that 
the  investigation  of  any  one  particular  species  will  bring  to  view, 
not  only  its  name  (which  separately  considered  is  of  little  im- 
portance), but  also  its  floral  structure,  affinities,  and  whole  natural 
history. 

679.  Such  a  system  must  of  course  be  natural;  that  is,  the 
groups,  of  whatever  rank,  must  be  composed  of  plants  more  close- 
ly related  to  each  other  than  to  any  different  groups,  and  so  ar- 
ranged that  each  shall  stand,  as  far  as  practicable,  next  to  those 
which  it  most  nearly  resembles  in  structure.  These  conditions 
are  so  far  fulfilled  by  the  Natural  System  (which,  sketched  by 
ihe  master-hand  of  Jussieu,  and  augmented  by  succeeding  bota- 
nists, is  now  generally  adopted),  as  to  render  it  on  the  whole 
far  the  readiest,  as  well  as  the  only  philosophical  and  satisfac- 
tory, method  of  acquiring  any  considerable  amount  of  botanical 
knowledge. 

680.  But  the  relationships  of  plants,  even  when  appreciated  by 
botanists,  could  not  be  made  available  for  the  purpose  of  classifi- 
cation, until  just  views  prevailed  in  vegetable  organography  and 
physiology,  which  constitute  the  very  foundation  of  Systematic 
Botany,  but  which  have  only  recently  been  placed  upon  a  philo- 
sophical basis.  Hence  the  immortal  Linnseus,  finding  it  impossi- 
ble in  his  day  to  characterize  the  natural  groups  which  his  prac- 
tised eye  detected,  proposed,  as  a  temporary  substitute,  the  elegant 

Tribe  is  applied  to  groups  comprised  in  a  suborder  (thus  the  Rose  constitutes 
a  separate  tribe  from  the  Raspberry,  Strawberry,  &c.),  or  to  the  primary  di- 
visions of  an  order,  when  they  are  not  founded  on  characters  of  high  impor- 
tance. In  a  loose  and  popular  sense,  the  name  of  Tribe  is  sometimes  used  as 
if  synonymous  with  that  of  Order  or  Family. 


356  CLASSIFICATION. 

artificial  scheme  which  bears  his  name.  As  this  system  is  identi- 
fied with  the  history  of  the  science,  which  in  its  time  it  so  greatly 
promoted,  and  as  most  systematic  works  have  until  recently  been 
arranged  upon  its  plan,  it  is  still  necessary  for  the  student  to  un- 
derstand it.  Fortunately,  its  principles  are  so  simple  that  a  brief 
space  will  amply  suffice  for  its  explanation. 


CHAPTER    II. 

OF    THE    ARTIFICIAL    SYSTEM    OF    LINNiEUS. 

681.  It  must  be  kept  in  mind,  that  an  artificial  scheme  does  not 
attempt  to  fulfil  all  the  conditions  of  natural  history  classification. 
Its  principal  object  is  to  furnish  an  easy  mode  of  ascertaining  the 
names  of  plants  ;  their  relationships  being  only  so  far  expressed  as 
the  plan  of  the  scheme  admits.  All  higher  considerations  are  of 
course  sacrificed  to  facility.  In  the  Linnaean  scheme,  the  species 
of  a  genus  are  always  kept  together,  whether  or  not  they  all  ac- 
cord with  the  class  or  order  under  which  they  are  placed.  Its 
lower  divisions,  therefore,  namely,  the  genera  and  species,  are  the 
same  as  in  a  natural  system.  But  the  genera  are  arranged  in  arti- 
ficial classes  and  orders,  founded  on  some  single  technical  charac- 
ter, and  have  no  necessary  agreement  in  any  other  respect ;  just 
as  words  are  alphabetically  arranged  in  a  dictionary,  for  the  sake 
of  convenience,  although  those  which  stand  next  each  other  have, 
it  may  be,  nothing  in  common  beyond  the  initial  letter. 

682.  The  classes  and  orders  Linna^.us  founded  entirely  upon  the 
number,  situation,  and  connection  of  the  stamens  and  pistils ;  the 
office  and  importance  of  which  he  had  just  set  in  a  clear  light. 

683.  The  classes,  twenty-four  in  number,  were  founded  upon 
modifications  of  the  stamens,  and  have  names  of  Greek  derivation 
expressive  of  their  character.  The  first  eleven  comprise  all  plants 
with  perfect  flowers,  and  a  definite  number  of  equal  and  uncon- 
nected stamens ;  they  are  distinguished  by  the  absolute  number  of 
these  organs,  and  are  designated  by  names  compounded  of  Greek 
numerals  and  the  word  andria  (from  dvrjp),  which  is  used  meta- 
phorically for  stamen  ;  as  follows  :  — 


THE    LINNJEAN    ARTIFICIAL    SYSTEM.  357 

Class  1.  MoNANDRiA  includes  all  such  plants  with  one  stamen  to 
the  flower ;  as  in  Hippuris  (Fig.  703). 

2.  DiANDRiA,  those  with  two  stamens,  as  in  the  Lilac. 

3.  Triandria,  with  three  stamens,  as  in  the  Valerian,  &c. 

(Fig.  764,  767). 

4.  Tetrandria,  with  four  stamens,  as  in  the  Plantain  (Fig. 

831). 

5.  Pentandria,  with  five  stamens,  the  most  frequent  case 

(Fig.  256,  335). 

6.  Hexandria,  with  six  stamens,  as  in  the  Lily  Family  (Fig. 

1108),  &c. 

7.  Heptandria,  with  seven  stamens,  as  in  the  Horsechest- 

nut  (Fig.  657). 

8.  Octandria,  with  eight  stamens,  as  in  the  Dirca   (Fig. 

1009). 

9.  Enneandria,  with  nine  stamens,  as  in  the  Rhubarb. 

10.  Decandria,  with  ten  stamens,  as  in  Fig.  285,  288. 

11.  DoDECANDRiA,  with  twclve  stamens,  as  in  Asarum  (Fig. 

968)  and  the   Mignonette ;    extended  also  to  include 
those  with  from  thirteen  to  nineteen  stamens. 
The  two  succeeding  classes  include  plants  with  perfect  flowers, 
having  twenty  or  more  unconnected  stamens,  which,  in 

12.  IcosANDRiA,  are  inserted  on  the  calyx  (perigynous,  466) 

as  in  the  Rose  Family  ;  and  in 

13.  PoLYANDRiA,  on  the  receptacle  (hypogynous),  as  in  the 

Buttercup,  Anemone  (Fig.  325),  &c. 
Their  essential  characters  are  not  designated  by  their  names ; 
the  former  merely  denoting  that  the  stamens  are  twenty  in  num- 
ber ;  the  latter,  that  they  are  numerous.     The  two  following  de- 
pend upon  the  relative  length  of  the  stamens,  namely, 

14.  DiDYNAMiA,  including  those  with  two  long  and  two  short 

stamens  (481,  Fig.  855) ;  and 

15.  Tetradynamia,  those  with  four  long  and  two  short  sta- 

mens, as  in  Cruciferous  flowers  (Fig.  526). 
Their  names  are  Greek  derivatives,  signifying  in  the  former  that 
two  stamens,  and  in  the  latter  that  four  stamens,  are  most  power- 
ful.    The  four  succeeding  are  founded  on  the  connection  of  the 
stamens  :  — 

16.  MoNADELPHiA  (meaning  a  single  fraternity),  with  the  fil- 

aments united  in  a  single  set,  tube,  or  column,  as  in 
Fig.  307,  and  in  all  the  Mallow  Family,  Fig.  617. 


358  CLASSIFICATION. 

Class  17.  DiADELPHiA  (two  fraternities),  with  the  filaments  united 
in  two  sets  or  parcels  (Fig.  296,  308,  320). 

18.  PoLYADELPHiA  (niany  fraternities),  with  the  filaments  unit- 

ed in  more  than  two  sets  or  parcels  (Fig.  300,  306). 

19.  Syngenesia  (from  Greek  words  signifying  to  grow  to- 

gether), with  the  anthers   united  in  a  ring    or  tube 
(Fig.  309,  310),  as  in  all  Composite  flowers. 
The  next  class,  as  its  name  denotes,  is  founded  on  the  union  of 
the  stamens  to  the  style  :  — 

20.  Gynandria,  with  the  stamens  and  styles  consolidated,  as 

in  the  Orchis  Family  (Fig.  1097). 
In  the  three  following,  the  stamens  and  pistils  are  separated 
(306) :  thus, 

21.  Mongecia  (one  household)  includes  plants  where  the  sta- 

mens and  pistils  are   in  separate  flowers  on  the  same 
individual ;  as  in  the  Oak  (Fig.  1042),  &c. 

22.  DicECiA  (two  households),  where  they  occupy  separate 

flowers  on  different  individuals  ;  as  in  the  Willow  (Fig. 
326-328),  Prickly  Ash  (Fig.  639-644),  &c. 

23.  PoLYGAMiA,  where  the  stamens  and  pistils  are  separate  in 

some  flowers  and  united  in  others,  either  on  the  same, 
or  two  or  three  different  plants ;   as  in  most  Maples 
(Fig.  647-649). 
The  remaining  class, 

24.  Cryptogamia,  is  said  to  have  concealed  stamens  and  pis- 

tils (as  the  name  imports),  and  includes  the   Ferns, 
Mosses,  Lichens,  &c.,  which  are  now  commonly  term- 
ed Cryptogamous  or  Flowerless  plants  (459). 
The  characters  of  the  classes  may  be  presented  at  a  single  view, 
as  in  the  subjoined  analysis  ;  — 


THE    LINNJEAN    ARTIFICAL   SYSTEM. 


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360  CLASSIFICATION. 

684.  The  orders,  in  the  first  thirteen  classes  of  the  Linnsean  ar- 
tificial system,  depend  on  the  number  of  styles,  or  of  the  stigmas 
when  the  styles  are  wanting;  and  are  named  by  Greek  numerals 
prefixed  to  the  word  gynia,  used  metaphorically  for  pistil,  as 
follows  :  — 

Order  1.  Monogynia  embraces  all  plants  of  any  of  the  first  thir- 
teen classes,  with  one  style  to  each  flower. 

2.  DiGYNiA  embraces  those  with  two  styles. 

3.  Trigynia,  those  with  three  styles. 

4.  Tetragynia,  those  with  four  styles. 

5.  Pentagynia,  those  with  five  styles. 

6.  Hexagynia,  those  with  six  styles. 

7.  Heptagynia,  those  with  seven  styles. 

8.  OcTOGYNiA,  those  with  eight  styles. 

9.  Enneagynia,  those  with  nine  styles. 

10.  Decagynia,  those  with  ten  styles. 

11.  Dodecagynia,  those  with  eleven  or  twelve  styles. 

12.  PoLYGYNiA,  those  with  more  than  twelve  styles. 
The  orders  of  class  14,  Didynamia,  are  only  two ;  namely, 

1.  Gymnospermia,  meaning  seeds  naked,  the  achenia-Iike 

fruits  having  been  taken  for  naked  seeds. 

2.  Angiospermia,  with  the  seeds  evidently  in  a  seed-vessel 

or  pericarp. 
The  15th  class,  Tetradynamia,  is  also  divided  into  two  orders, 
which  are  distinguished  by  the  mere  form  of  the  pod  :  — 

1.  SiLicuLOSA  ;  the  fruit  a  silicle  (615),  or  short  pod. 

2.  Siliquosa;  fruit  a  silique  (615),  or  more  or  less  elongat- 

ed pod. 

The  orders  of  the  16th,  17th,  18th,  20th,  21st,  and  22d  classes 
depend  merely  on  the  number  of  stamens ;  that  is,  on  the  charac- 
ters of  the  first  thirteen  classes,  whose  names  they  likewise  bear  : 
thus. 

Order  1.  Monandria  ;  2.  Diandria;  and  so  on. 

The  orders  of  the  19th  class,  Syngenesia,  are  six;  namely, 

1.  Polygamia  jEQUAlis,  where  the  flowers  are  in  heads  (com- 

pound, 394),  and  all  perfect. 

2.  Polygamia  superflua,  the  same  as  the  last,  except  that 

the  rays,  or  marginal  flowers  of  the  head,  are  pistillate 
only  (473). 


THE    NATURAL    SYSTEM.  361 

3.  PoLYGAMiA  FRUSTRANEA,  those  with  the  marginal  flowers 

neutral  (473,  note),  the  others  perfect. 

4.  PoLYGAMiA  NECESSARiA,  where  the   marginal  flowers  are 

pistillate  and  fertile,  and  the  central  (those  of  the  disk) 
staminate  and  sterile. 

5.  PoLYGAMiA  SEGREGATA,  whcro  cach  flowor  of  the  head  has 

its  own  proper  involucre. 

6.  MoNOGAMiA,  where  solitary  flowers  (that  is,  not  united  into 

a  head)   have  united  anthers,  as  in  Lobelia.      This 
order  was  abolished  by  succeeding  Linnsean  botanists. 
The  23d  class,  Polygamia,  has  three    orders,  founded  on  the 
characters  of  the  two  preceding  classes  ;  namely, 

1.  MoNOECiA,  where  both  separated  and  perfect  flowers  are 

found  in  the  same  individual. 

2.  DiCEciA,  where  they  occupy  difierent  individuals. 

3.  Tricecia,  where  one  individual  bears  the  perfect,  another 

the  staminate,  and  a  third  the  pistillate  flowers. 
The  orders  of  the  24th  class,  Cryptogamia,  are  natural,  and 
therefore  indefinable  by  a  single  character.     They  are, 

1.  FiLicES,  the  Ferns. 

2.  Musci,  the  Mosses. 

3.  Algje,  which,  as  left  by  Linnseus,  comprised  the  Hepaticse, 

Lichens,  &c.,  as  well  as  the  Seaweeds. 

4.  Fungi,  Mushrooms,  &c. 


CHAPTER    III. 

OF    THE    NATURAL    SYSTEM. 

685.  The  object  proposed  by  the  Natural  System  of  Botany  is 
to  bring  together  into  groups  those  plants  which  most  nearly  re- 
semble each  other,  not  in  a  single  and  perhaps  unimportant  point 
(as  in  an  artificial  classification),  but  in  all  essential  particulars  ; 
and  to  combine  the  subordinate  groups  into  larger  natural  assem- 
blages, and  these  into  still  more  comprehensive  divisions,  so  as  to 
embrace  the  whole  vegetable  kingdom  in  a  methodical  arrange- 
ment. All  the  characters  which  plants  present,  that  is,  all  the 
31 


m^ 


CLASSIFICATION. 


points  of  agreement  or  difference,  are  employed  in  their  classifica- 
tion ;  those  which  are  common  to  the  greatest  number  of  plants 
being  used  for  the  primary  grand  divisions ;  those  less  compre- 
hensive for  subordinate  groups,  &c. ;  so  that  the  character  (678), 
or  description  of  each  group,  when  fully  given,  actually  expresses 
all  the  known  particulars  in  which  the  plants  it  embraces  agree 
among  themselves,  and  differ  from  other  groups  of  the  same  rank. 
This  complete  analysis  being  carried  through  the  system,  from  the 
primary  divisions  down  to  the  species,  it  is  evident  that  the  study 
of  a  single  plant  of  each  group  will  give  a  correct  general  idea  of 
the  structure,  habits,  and  even  the  sensible  properties,  of  the  whole. 

686.  What  we  call  a  natural  method,  it  may  here  be  remarked, 
is  so  termed  merely  because  it  expresses  the  natural  relationship 
of  plants  as  far  as  practicable  ;  for  every  form  yet  contrived,  or 
likely  to  be  devised,  is,  to  a  considerable  extent,  artificial :  — 
1st.  Because  the  affinities  of  a  particular  group  cannot  be  fully 
estimated  until  all  its  members  are  known  ;  and  thus  the  progress 
of  discovery  leads  to  changes,  or  modifies  our  views,  as  in  every 
other  department  of  knowledge.  2d.  Because  the  boundaries  of 
groups  are  not  so  arbitrarily  circumscribed  in  nature,  as  they  ne- 
cessarily are  in  our  classifications ;  but  individuals  depart  from  the 
assigned  limits  in  various  directions  (like  rays  from  a  centre) ; 
the  "  edge  of  difference  being,  as  it  were,  softened  down  by  an 
easy  transition."  3d.  Because,  even  supposing  the  groups  to  be 
perfectly  natural,  and  their  affinities  completely  understood,  it  is 
impossible  to  arrange  them  in  a  single  continuous  series,  in  such  a 
manner  that  each  shall  be  preceded  and  followed  by  its  nearest 
allies ;  since  the  same  family,  for  instance,  may  be  about  equally 
related  to  three  or  four  others,  only  two  of  which  points,  at  best, 
can  be  indicated  in  the  lineal  series  which  must  be  adopted  in 
books.  And  4th.  We  are  still  obliged  to  use  avowedly  artificial 
characters,  for  the  sake  of  convenience  ;  as  in  the  arrangement  of 
the  numerous  orders  of  Exogenous  plants  into  the  Polypetalous, 
Monopetalous,  and  Apetalous  divisions  of  the  series,  although  dif- 
ferent genera  of  the  same  order,  or  different  species  of  the  same 
genus,  may  present  these  very  diversities. 

687.  In  explaining  the  general  principles  of  classification,  we 
proceeded  from  the  individual  to  the  class  ;  showing  how  groups 
of  successive  rank  arise  from  the  consideration  of  points  of  agree- 
ment.    In  applying  them  to  the  actual  distribution  of  plants  ac- 


THE    NATURAL    SYSTEM.  363 

cording  to  the  received  mode  of  classification,  it  will  be  more  con- 
venient to  pursue  the  analytical  course,  and  to  show  how  the  veg- 
etable kingdom,  taken  as  a  whole,  is  divided  and  subdivided,  by 
regarding  the  points  of  difference. 

688.  The  general  plan  upon  which  the  vegetable  creation  is 
constituted,  it  has  been  the  object  of  the  whole  former  part  of  this 
treatise  to  illustrate  :  the  fundamental  principles  of  natural  history 
classification  have  also  been  cursorily  expounded  in  a  preceding 
chapter.  In  applying  the  one  to  the  other,  we  have  to  consider,  in 
the  first  place,  how  the  long  series,  reaching  from  the  highest 
Flowering  plants  to  the  lowest  and  minutest  Fungi  and  Algse,  can 
be  primarily  divided.  As  already  intimated,  the  most  decided 
break  in  the  series  occurs  between  the  flower-bearing  and  the  flow- 
erless  plants  ;  the  first  producing  proper  flowers  (with  stamens  and 
pistils)  and  seeds  containing  a  ready  formed  embryo ;  while  in  the 
second,  these  are  replaced  by  a  more  or  less  analogous,  but  sim- 
pler and  more  recondite  apparatus.  We  need  only  refer  to  those 
paragraphs  in  which  the  difference  is  brought  to  view  (109,  &c.). 
The  vegetable  kingdom,  viewed  under  this  aspect,  is  therefore  pri- 
marily divided  into  two  series,  a  higher  and  a  lower,  the  Flower- 
ing and  the  Flowerless,  or  (under  other  and  older  names)  the 
Phjenogamous  (or  Phanerogamous)  and  the  Cryptogamous  plants- 

689.  Let  us  next  consider  how  the  higher  series,  embracing  far 
the  larger  part  as  well  as  the  most  complex  forms  of  the  vegetable 
kingdom,  may  itself  be  divided,  in  view  of  the  most  general  and 
important  points  of  difference  which  the  plants  it  comprises  exhibit. 
Whenever  they  rise  to  arborescent  forms,  a  difference  in  port  and 
aspect  at  once  arrests  attention  ;  that  which  distinguishes  our  com- 
mon trees  and  shrubs  from  Palms  and  the  like  (Fig.  220).  On 
examination,  this  difTerence  is  found  to  be  connected  with  an  im- 
portant difTerence  in  the  structure  of  the  stem  or  wood,  and  in  its 
mode  of  growth.  The  former  present  the  exogenous,  the  latter  the 
endogenous  structure  or  growth  (184-187).  This  difTerence  is 
manifest,  although  not  so  striking,  in  the  annual  or  herbaceous 
stems  of  these  two  sorts  of  Phaenogamous  plants.  A  difference  is 
also  apparent  in  their  foliage ;  the  former  generally  have  reticu- 
lated^ or  netted'veined,  the  latter  parallel-veined  leaves  (276). 
The  leaves  of  the  former  usually  fall  off  by  an  articulation  ;  those 
of  the  latter  decay  on  the  stem  (309,  310).  The  Phaenogamous 
series,  therefore,  divides  into  two  great  classes,  namely,  into  Exoge- 


364  CLASSIFICATION. 

2T0trs  and  Exdoge^tous  plants,  more  briefly  named  Eiogexs  and 
ExDOGE?fs.  The  difference  between  the  two 'not  only  pervades 
their  whole  port  and  aspect,  but  is  manifest  from  the  earliest  stage. 
The  embryo  of  Exogens,  as  already  shown,  is  provided  with  a  pair 
of  cotyledons,  that  of  Endogens  with  only  one ;  whence  the  for- 
mer are  also  termed  Dicottledonofs,  and  the  latter  Monocott- 
LEDONOUS  plants  :  names  introduced  by  Jussieu,  the  father  of  this 
branch  of  botany.  We  employ  sometimes  the  one  and  sometimes 
the  other  of  the  two  sorts  of  names  for  these  two  great  classes. 

690.  In  contemplating  the  Exogenous  or  Dicotyledonous  class, 
we  find  that  two  sets  of  the  plants  it  comprises  are  specially  dis- 
tinguished by  a  great  simplicity  in  their  organs  of  fructification, 
approximating  not  indistinctly  to  that  still  greater  simplicit}-  which 
characterizes  the  highest  Cryptogamous  plants  (108).  These  are 
the  Coniferous  trees,  such  as  Pines,  Firs,  dec,  and  that  small  and 
singular  tribe  of  Endogenous  port  but  essentially  Exogenous  struc- 
ture, which  comprises  the  Cycas  and  Zamia  (Fig.  403) :  in  these 
cases,  not  only  are  the  sterile  or  staminate  flowers  reduced  to  the 
last  degree  of  simplicity,  but  the  fertile  consist  of  naked  ovules 
merely,  borne  on  the  margins  or  surface  of  a  sort  of  open  leaf,  in- 
stead of  being  inclosed  in  an  ovary  (560,  111).  They  are  there- 
fore named  Gymnospermous  (that  is,  naked-seeded)  plants  ;  and 
form  a  subordinate  group,  or  subclass,  of  Exogens.  When  it  is 
needful  to  contradistinguish  the  great  mass  of  Exogens  from  which 
these  are  thus  separated,  we  call  them  Angiospermous  Exogenous 
plants  ;  a  name  denoting  that  their  seeds  are  inclosed  in  a  pericarp. 
No  such  reduction  occurs  in  the  Endogenous  class. 

691.  We  must  next  consider  the  systematic  division  of  the  Flow- 
erless,  or  Cryptogamous  series.  This  is  most  readily  accomplished 
by  conceiving  them  to  present  a  series  of  reductions  or  degrada- 
tions of  a  higher  type.  In  their  general  mode  of  growth,  and  in 
their  anatomical  structure,  the  higher  Flowerless  plants,  such  as 
Equisctums,  Club-Mosses,  and  Ferns,  do  not  essentially  differ  from 
Flowering  plants.  All  the  various  kinds  of  elementary  tissue, 
proper  woody  fibre,  vessels,  d^c,  enter  into  their  composition  (108, 
109).  If  we  had  chosen  to  take  anatomical  structure  as  the  basis 
of  our  primary  division  of  the  whole  vegetable  kingdom,  we  might 
have  divided  the  whole  into  Vascular  and  CeUular  plants  (107),  as 
was  done  by  De  CandoUe  ;  the  former  comprising  the  whole  series 
from  Ferns  upward,  the  latter  embracing  the  Mosses  and  all  below 


THE   NATURAL    SYSTEM. 


365 


them.  Flaving  effected  the  primary  division,  however,  upon  other 
grounds,  we  turn  this  difference  to  subordinate  account ;  and 
therefore  consider  the  higher  Flowerless  plants,  which  agree  with 
the  series  above  them  in  so  many  respects,  and  which  in  their 
composition  have  woody  tissue  and  vessels,  to  constitute  the  dis- 
tinct class  of  Vascular  Flowerless  plants.  For  reasons  already 
explained  (108),  they  have  also  been  termed  Acrogens.  All  the 
kinds  below  these,  being  composed  of  cellular  tissue  exclusively, 
(though  the  cells  are  often  drawn  into  filaments,  which  may  even 
have  a  spiral  fibre  generated  upon  their  walls,)  are  Cellular  plants. 

692.  But  the  higher  Cellular  plants,  such  as  Mosses,  still  dis- 
play the  proper  type  of  vegetation  ;  they  agree  with  those  of  high- 
er grades  in  having  an  opposite  growth,  forming  a  distinct  axis  or 
stem,  which  grows  upward  by  buds  and  is  for  the  most  part  sym- 
metrically clothed  with  distinct  leaves  ( 105) ;  while  the  Lichens, 
Seaweeds,  and  Fungi,  the  most  imperfect  of  vegetables,  present 
no  distinction  into  stem,  root,  and  leaves,  no  polarity,  or  growth  in 
two  opposite  directions,  no  buds,  and  no  organs  which  are  clearly 
analogous  to  flowers.  Their  homogeneous  tissue  often  tends  to  the 
formation  of  flat,  more  or  less  definite  expansions  (the  thallus)^ 
which  is  the  nearest  approach  to  any  thing  like  leaves ;  in  which 
their  simple  spores  are  embedded.  Hence  they  are  termed  Thai' 
lophytes.  If  the  line  of  primary  division  be  drawn  in  view  of  these 
importemt  distinctions,  as  proposed  by  Unger  and  Endlicher,  the 
vegetable  kingdom  would  be  separated  into  two  great,  but  unequal 
series  ;  namely,  1st,  the  Comwphytes^  or  Stem-growing  plants^  — 
those  with  a  distinct  axis  of  growth,  elongating  downward  into 
roots,  and  upward  into  stems,  provided  with  leaves,  and  with  flow- 
ers or  their  analogues ;  and  2d,  the  ThaUophyfes,  which  are  stem- 
less,  rootless,  leafless,  and  in  every  sense  flowerless  (106). 

693.  Following  the  plan  we  have  adopted,  however,  we  have 
only  to  distinguish  this  higher  grade  of  Flowerless  Cellular  plants, 
exhibiting  a  distinct  stem,  &c.,  as  a  separate  class,  the  Anophytes, 
represented  by  the  Mosses,  which,  although  of  the  simplest  ana- 
tomical structure,  still  emulate  the  higher  or  typical  forms  (105), 
The  remainder  (94-103),  embracing  the  Lichens,  Fungi,  and 
Algse,  form  the  last  and  lowest  class,  the  Thallophttes.  To  con- 
sider their  subordinate  arrangement  would  quite  surpass  our  limits. 

694.  The  general  plan  may  be  analytically  expressed  by  the 
following  schedule. 

31* 


CLASSIFICATION. 


o 

2 

s 

S 

a 

>< 

aj 

<5 

o 

>; 

^ 

oi 

O 

w 

J 

y^ 

o 

:: 

^ 

3 
CO 

Q 

Q 

. 

o< 

fi 

!3 

NOMENCLATURE.  367 

695.  These  five  classes  are  very  unequal,  in  respect  to  the 
number  of  plants  they  embrace ;  the  Exogenous  class  containing 
much  the  largest  number  of  species  as  well  as  orders ;  the  Endo- 
gens  also  comprising  numerous  types ;  but  the  others  very  few  in 
comparison.  Convenience  of  analysis  therefore  requires  that  the 
larger  classes  should  be  broken  up  into  divisions,  alliances,  co- 
horts, or  by  whatever  name  groups  intermediate  between  the 
classes  and  orders  may  be  termed :  and  the  accomplishment  of 
this  object,  so  as  to  form  natural  groups,  is  at  present  the  great  de- 
sideratum in  Systematic  Botany.  But  until  this  be  well  done,  we 
are  obliged  to  use  artificial  analyses  of  the  classes,  or  to  thro^v  the 
orders  into  groups,  which,  in  proportion  as  they  are  rendered  natu- 
ral, it  becomes  impossible  strictly  to  circumscribe.  In  this  view, 
the  great  class  of  Exogenous  plants  is  usually  broken  up  into  three 
very  convenient,  but  nearly  artificial  portions,  founded  on  the  pres- 
ence, absence,  or  union  of  the  petals  ;  namely  : 

1.  PoLYPETALiE,  the  Polypctalous  Exogens ;    where  the  calyx 

and  corolla  are  both  present,  and  the  latter  composed  of 
distinct  petals. 

2.  MoNOPETAL^  or'  Gamopetal^,  the  Monopetalous  Exogens ; 

where  the  petals  are  united. 

3.  Apetalje,  the  Apetalous  Exogens  ;    where   the  petals  are 

wanting,  and  the  floral  envelopes,  if  present  at  all,  consist 
of  the  calyx  alone. 

696.  These  divisions,  as  well  as  the  other  classes,  are  subdi- 
vided by  different  authors  in  various  ways,  which  need  not  be  spe- 
cified ;  since  it  is  only  the  classes  and  the  orders  that  are  consid- 
ered to  rest  upon  a  stable  basis. 

697.  The  orders,  or  families,  are  to  be  viewed  rather  as  natural 
groups  of  genera,  than  as  subdivisions  of  the  classes.  The  kind  of 
characters  employed  in  distinguishing  them  will  best  be  learned 
from  the  succeeding  illustrations. 

698.  Nomenclature.  Their  names,  which  are  always  plural,  some- 
times express  a  characteristic  feature  of  the  group  ;  as,  for  in- 
stance, Leguminoscc,  or  the  Leguminous  plants,  such  as  the  Pea, 
Bean,  &c.,  whose  fruit  is  a  legume  (603) ;  UmhelUferce,  or  Um- 
belliferous plants,  so  named  from  having  the  flowers  in  umbels ; 
Composit(E,  an  order  having  what  were  termed  compound  flowers 
by  the  earlier  botanists  (394) ;  Labiatce,  so  called  from  the  labiate 


368  CLASSIFICATION. 

or  two-lipped  corolla  (511),  which  nearly  all  the  species  exhibit; 
Cruciferce,  which  have  their  four  petals  disposed  somewhat  in  the 
form  of  a  cross,  &;c.  But  more  frequently,  and  indeed  as  a  gen- 
eral rule,  the  name  is  formed  from  that  of  some  leading  or  well- 
known  genus,  which  is  prolonged  into  the  adjective  termination 
acecB.  Thus,  the  plants  of  the  order  which  comprises  the  Mallow 
(Malva)  are  called  Malvacece ;  that  \s,  PlaritcR  MalvacecB,  or,  in 
English,  Malvaceous  plants  :  those  of  which  the  Rose  {Rosa)  is 
the  well-known  representative  are  RosacecB,  or  Rosaceous  plants, 
&c.  This  termination  in  acece,  being  reserved  for  orders,  should 
not  lie  applied  to  suborders  or  tribes,  which  usually  bear  the  name 
of  their  principal  or  best-known  genus  in  an  adjective  form,  with- 
out such  prolongation.  Thus  the  genus  Rosa  gives  name  to  a  par- 
ticular tribe,  Rosecs,  of  the  order  Rosacece ;  the  genus  Malva  to  the 
tribe  Malvece  of  the  order  Malvacece,  &c. 

699.  The  number  of  genera  in  an  order  is  quite  as  indefinite  as 
that  of  the  orders  in  a  class,  or  other  great  division.  While  some 
orders  are  constituted  of  a  single  genus,  as  Equisetacece,  Grossu- 
lacese,  &c.  (just  as  many  genera  contain  but  a  single  known  spe- 
cies), others  comprise  a  large  number  of  genera ;  nearly  nine 
hundred  beiiig  embraced  in  the  last  general  enumeration  of  the 
Compositse. 

700.  The  names  of  genera  are  Latin  substantives,  in  the  singu- 
lar number,  and  mostly  of  Greek  or  Latin  derivation.  Those 
which  were  known  to  the  ancients  generally  preserve  their  classi- 
cal appellations  (Ex.  Fagus,  Prunns,  Myrtus,  Viola ^  &c.)  ;  and 
even  the  barbarous  or  vulgar  names  of  plants  are  often  adopted, 
when  susceptible  of  a  Latin  termination,  and  not  too  uncouth  ;  for 
example,  ThcBa  and  Coffc^a,  for  the  Tea  and  Coffee  plants,  Bam- 
husa  for  the  Bamboo,  Yucca,  Negundo,  &:c.  But,  more  common- 
ly, generic  names  are  formed  to  express  some  botanical  character, 
habit,  or  obvious  peculiarity  of  the  plants  they  designate  ;  such  as 
Arenaria,  for  a  plant  which  grows  in  sandy  places ;  Dentaria,  for 
a  plant  with  toothed  roots  ;  Lunaria,  for  one  with  moon-shaped 
pods;  Sanguinaria,  for  the  Blood  root ;  Cr  as  sula,  for  some  plants 
with  remarkably  thick  leaves.  These  are  instances  of  Latin  deriv- 
atives ;  but  recourse  is  more  commonly  had  to  the  Greek  language, 
especially  for  generic  names  composed  of  two  words ;  such  as 
Menispermum,  or  Moonseed  ;  Lithospermum,  for  a  plant  with  stony 
seeds;  Melanthium,  for  a  genus  whose  flowers  turn  of  a  black  or 


NOMENCLATURE.  369 

dusky  color ;  Epidendrum,  for  Orchideous  plants  which  grow  upon 
trees ;  Liriodendron^  for  a  tree  which  bears  lily-shaped  flowers, 
&c.  Genera  are  also  dedicated  to  distinguished  persons,  a  prac- 
tice commenced  by  the  ancients ;  as  in  the  case  of  Pceonia,  which 
bears  the  name  of  Pseon,  who  is  said  to  have  employed  the  plant 
in  medicine  ;  and  Euphorhia,  Artemisia^  and  Asclepias  are  also 
examples  of  the  kind.  Modern  names  of  this  kind  are  given  in 
commemoration  of  botanists,  or  of  persons  who  have  contributed 
to  the  advancement  of  natural  history.  Magnolia^  Bignonia,  Lo- 
lelia,  and  Lonicera,  dedicated  to  Magnol,  Bignon,  Lobel,  and  Lo- 
nicer,  are  early  instances  of  the  practice  ;  Linnsea,  Tournefortia, 
JussisBa,  Gronovia,  &;c.,  bear  the  names  of  more  celebrated  bota- 
nists ;  and  at  the  present  day  almost  every  devotee  or  patron  of 
the  science  is  thus  commemorated. 

701.  The  names  of  species,  as  a  general  rule,  are  adjectives, 
written-  after  those  of  the  genera,  and  established  on  similar  princi- 
ples ;  as.  Magnolia  grandiflora,  the  Large-flowered  Magnolia  ; 
M.  macrophylla,  the  Large-leaved  Magnolia  ;  Bignonia  radicans, 
the  Rooting  Bignonia,  &c.  The  generic  and  specific  names,  taken 
together,  constitute  the  proper  scientific  appellation  of  the  plant. 
Specific  names  sometimes  distinguish  the  country  which  a  plant 
inhabits  (Ex.  Viola  Canadensis,  the  Canadian  Violet) ;  or  the  sta- 
tion where  it  naturally  grows  (as  V.  palustris,  which  grows  in 
swamps,  V.  arvensis,  in  fields,  &c.) ;  or  they  express  some  obvious 
character  of  the  species  (as  V.  rostrata,  where  the  corolla  bears 
a  remarkably  long  spur ;  V.  tricolor,  which  has  tricolored  flow- 
ers ;  V,  rotundifolia,  with  rounded  leaves ;  V.  lanceolata,  with 
lanceolate  leaves ;  F.  pedata,  with  pedately  parted  leaves ;  V.  pri- 
mulcsfoUa,  where  the  leaves  are  compared  to  those  of  the  Prim- 
rose ;  V.  asarifolia,  where  they  are  likened  to  those  of  Asarum  ; 
V.  puhescens,  which  is  hairy  throughout,  &c.).  Frequently  the 
species  bears  the  name  of  its  discoverer  or  describer,  when  it  takes 
the  genitive  form,  as  Viola  Muhlenlergii,  V.  Nutiallii,  (fee.  When 
such  commemorative  names  are  merely  given  in  compliment  to  a 
botanist  unconnected  with  the  discovery  or  history  of  the  plant,  the 
adjective  form  is  preferred  ;  as  Carex  Torreyana,  C.  Hookeriana, 
&c. :  but  this  rule  is  not  universally  followed.  Specific  names  are 
sometimes  substantive  ;  as  Ranunculus  Flammula,  Hypericum  Sa- 
rothra,  Linaria  Cymhalaria,  &c. ;  when  they  do  not  necessarily 
accord  with  the  genus  in  gender.     These,  as  well  as  all  specific 


370 


CLASSIFICATION. 


names  derived  from  those  of  persons  or  countries,  should  always 
be  written  with  a  capital  initial  letter. 

702.  In  an  exposition  of  the  natural  system,  some  authors  (such 
as  Jussieu  and  Endlicher)  commence  with  the  lower  extremity  of 
the  series,  and  end  with  the  higher ;  while  others  (as  De  Candolle) 
pursue  the  opposite  course,  beginning  with  the  most  perfect  Flow- 
ering plants,  and  concluding  with  the  lowest  grade  of  Flowerless 
plants.  The  first  mode  possesses  the  advantage  of  ascending  by 
successive  steps  from  the  simplest  to  the  most  complex  structure  ; 
the  second,  that  of  passing  from  the  most  complete  and  best  under- 
stood to  the  most  reduced  and  least  known  forms ;  or,  in  other 
words,  from  the  easiest  to  the  most  difficult ;  and  is  therefore  the 
best  plan  for  the  student. 

703.  The  arrangement  of  De  Candolle,  being  most  in  use,  has 
been  followed  as  nearly  as  practicable  in  the  following  illustrations, 
so  far  as  relates  to  the  sequence  of  the  orders.  In  the  conspectus, 
these  have  been  thrown  into  small,  and  more  or  less  natural  groups, 
the  characters  of  which,  imperfect  as  they  must  be,  will  serve 
as  a  kind  of  key  to  the  orders  of  each  class  or  subclass,  and  facili- 
tate in  some  degree  the  student's  investigation.*  It  is  by  no  means 
necessary,  or  desirable,  to  introduce  into  our  elementary  illustra- 
tions the  little  known  and  unimportant  orders,  especially  those 
which  have  no  indigenous,  naturalized,  or  commonly  cultivated 
representatives  in  the  United  States.  Those  more  important  ex- 
otic families,  however,  which  would  otherwise  be  omitted,  are 
mentioned  in  the  form  of  notes,  placed  at  the  bottom  of  the  page, 
under  the  indigenous  orders  to  which  they  are  respectively  related. 
Full  descriptions  of  the  orders  have  not  been  attempted,  but  the 
easier  distinguishing  characters  are  given,  to  the  exclusion  of  the 
non-essential.  An  explanation  of  the  technical  terms,  which,  for 
obvious  reasons,  are  freely  employed,  (and  which  will  serve  to  ini- 
tiate the  student  into  the  language  of  descriptive  botany,)  may  be 
sought  in  the  combined  glossary  and  index  at  the  end  of  the 
volume. 

*  In  a  Flora,  or  other  systematic  work  based  on  the  natural  system,  artifi- 
cial analyses,  contrived  in  various  ways,  are  necessary  to  the  unpractised  stu- 
dent, and  afford  him  great  assistance  in  disentangling  the  more  or  less  compli- 
cated characters  of  the  orders.  But  tliey  are  hardly  necessary  in  our  sketch, 
which  is  intended  to  give  a  cursory  general  view  of  the  principal  natural  or- 
ders, rather  than  a  particular  and  systematic  analysis. 


THE  POLYPETALOUS  ORDERS.  371 


CHAPTER     IV. 


ILLUSTRATIONS    OF    THE    NATURAL    ORDERS    OR    FAMILIES. 

Series  I.     Flowering,  or  Phjenogamous  Plants. 

Plants  furnished  with  flowers  (essentially  consisting  of  stamens 
and  pistils),  and  producing  proper  seeds  (110,  414). 

Class  I.     Exogenous  or  Dicotyledonous  Plants. 

Stem  consisting  of  a  distinct  bark  and  pith,  which  are  separated 
by  an  interposed  layer  of  woody  fibre  and  vessels,  forming  wood 
in  all  perennial  stems :  increase  in  diameter  effected  by  the  annual 
deposition  of  new  layers  between  the  old  wood  and  the  bark,  which 
are  arranged  in  concentric  zones  (189-205),  and  traversed  by 
medullary  rays.  Leaves  commonly  articulated  with  the  stem 
(310),  their  veins  branching  and  reticulated  (276).  Sepals  and 
petals,  when  present,  more  commonly  in  fives  or  fours,  and  very 
rarely  in  threes.    Embryo  with  two  or  more  cotyledons  (633,  640). 

Subclass  1.     Angiospermous  Exogenous  Plants. 

Ovules  produced  in  a  closed  ovary,  and  fertilized  by  the  action 
of  pollen  through  the  medium  of  a  stigma.  Embryo  with  a  pair 
of  opposite  cotyledons  (633). 

Division  I.     Polypetalous  Exogenous  Plants. 

Floral  envelopes  consisting  of  both  calyx  and  corolla  ;  the  petals 
distinct.* 

Conspectus  of  the  Orders. 

Group  1.  Ovaries  several  or  numerous  (in  a  few  cases  solitary),  distinct, 
when  in  several  rows  sometimes  cohering  in  a  mass,  but  not  united  into 
a  compound  pistil.-    Petals  and  stamens  hypogynous.     Seeds  albuminous. 

*  Stamens  or  pistils  (one  or  both)  numerous  or  indefinite. 
Herbs,  without  stipules.  RANCNCuLACEi3E,  p.  376. 

*  Some  cases  of  polypetalous  flowers  also  occur  in  the  orders  Ericacege, 
Aquifoliaceae,  and  Plumbaginaceee,  which  are  placed  in  the  Monopetalous 
part  of  the  series ;  and  some  genera  of  several  orders  placed  here  are  apeta- 
lous,  such  as  Anemone,  &c. 


372  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Shrubs  or  trees,  witli  stipules;  aestivation  imbricative.    Magnoliace^,  p.  377. 
Without  stipules  ;  aestivation  valvular.       ANONACEiE,  p.  378. 

»  Stamens  few  or  definite.     Pistils  few  or  solitary. 
Climbing  plants.    Mono -dioecious.  MenispermacjE,  p.  379. 

Shrubs  or  herbs.     Flowers  perfect.  Berberidaceje,  p.  380. 

Group  2.  Ovaries  several,  either  distinct,  or  perfectly  united  into  a  com- 
pound pistil  of  several  cells.  Stamens  definite  or  indefinite,  inserted  on 
the  receptacle  or  torus.  Embryo  inclosed  in  a  sac  at  the  end  of  the  albu- 
men, or  in  Nelumbium  without  albumen.    Aquatic  herbs. 

Carpels  distinct  and  free.     Stamens  6 -18.  Cabombaceje,  p.  381. 

Carpels  distinct,  immersed  in  a  dilated  torus.  Nelumbiaceje,  p.  382. 

Carpels  united  in  a  several-celled  many-ovuled  ovary.   Nymph-eace^,  p.  383. 

Group  3.  Ovary  compound,  5-celled,  with  the  placentae  in  the  axis.  Sta- 
mens hypogynous,  indefinite.  Seeds  numerous,  anatropous,  albuminous, 
with  a  small  embryo.  Marsh  herbs,  with  pitcher-shaped  or  tubular 
leaves.  SarraceniacejE,  p.  383. 

Group  4.  Ovary  compound,  with  parietal  placentae.  Calyx  and  corolla 
2 -4-merous,  deciduous.  Stamens  hypogynous.  Flower  unsymmetrical. 
Embryo  small  in  copious  albumen,  or  coiled  when  there  is  no  albumen. 

Seeds  albuminous:  embryo  small  or  minute. 

Polyandrous:  flower  regular.  Papaverace^,  p.  383. 

Diadelphous  or  hexandrous  :  flower  irregular.  FuMARiACEiE,  p.  385. 
Seeds  without  albumen  :  styles  and  stigmas  united. 

Pod  two-celled.     Radicle  folded  on  the  cotyledons.  Cruciferje,  p.  385. 

Pod  one-celled.     Embryo  rolled  up.  Capparidaceje,  p.  386. 

Seeds  without  albumen.     Styles  or  stigmas  several.  Resedaceje,  p.  387. 

Group  5.  Ovary  compound,  with  parietal  placentae.  Floral  envelopes 
mostly  5-merous ;  the  calyx  persistent.  Stamens  hypogynous.  Seeds 
albuminous. 

Anthers  (5)  adnate,  inlrorse,  connate.     Corolla  irregular.    ViOLACEiE,  p.  387. 
Anthers  extrorse,  or  innate,  distinct.     Corolla  regular. 

Vernation  circinate.     Petals  marcescent.  Droserace^e,  p.  388. 

Vernation  straight.     Petals  usually  caducous.  Cistace^,  p.  389. 

Group  6.  Ovary  compound  with  the  placentae  parietal,  or  2- 5-celled  from 
their  meeting  in  the  axis.  Stamens  hypogynous.  Seeds  with  a  straight 
embryo  and  very  little  or  no  albumen. 

Sterile  filaments  or  a  lobed  appendage  before  each  petal.   Parnassie^e,  p.  389. 
Sterile  filaments  none  :  leaves  opposite.  • 

Stipules  none;  leaves  dotted.  Stam.  unsymmetrical.  Hvpericace^,  p.  390. 

Stipules  present:  leaves  dotless.    Stam.  symmetrical.   Elatinace-s,  p.  391. 

Group  7.     Ovary   compound,   one-celled   with   a  free   central   placenta,  or 

2-several-ceIled  with  the  placenta  in  the  axis.     Calyx  free  or  nearly  so. 

Stamens  hypogynous  or  perigynous.     Embryo  peripheric,  coiled  more  or 

less  around  the  outside  of  mealy  albumen. 


THE    POLYPETALOUS    ORDERS.  373 

Petals  numerous.     Ovary  many-celled.  Mesembryanthemaceje,  p.  394. 

Floral  envelopes  symmetrical.     Stamens  no  more  than  10. 

Caryophvllace-s,  p.  391. 

Floral  envelopes  unsymmetrical,  or  polyandrous.     Portulacace^,  p.  393. 
Petals  3-5  or  6,  sometimes  wanting. 

Group  8.  Ovary  compound  and  several-celled,  with  the  placenta  in  the 
axis ;  or  the  numerous  carpels  more  or  less  coherent  with  each  other  or 
with  a  central  axis.  Calyx  free  from  the  ovary,  with  a  valvate  aestiva- 
tion. Stamens  mostly  indefinite,  monadelphous,  or  polyadelphous,  in- 
serted with  the  petals  into  the  receptacle  or  base  of  the  petals. 

Anthers  1-celled.    Stamens  monadelphous.  Malvaceae,  p.  394. 

Anthers  2-celled.  Fertile  stam.  few,  monadelphous.  ByTTNERiACEiE,  p.  395. 
Anthers  2-celled.     Stamens  polyandrous  or  5-adelphous.      Tiliace^,  p.  395. 

Group  9.  Ovary  compound,  with  two  or  more  cells,  and  the  placentae  in  the 
axis,  free  from  the  calyx,  which  is  imbricated  in  aestivation.  Stamens 
indefinite,  or  twice  as  many  as  the  petals,  usually  monadelphous,  hypo- 
gynous.  —  Trees  or  shrubs. 

Leaves  simple,  not  dotted.  Stamens  indefinite.  Ternstr(Emiaceje,  p.  397. 
Leaves  pellucid-punctate,  mostly  compound.  Aurantiaceje,  p.  397. 

Leaves  compound,  dotless.     Stamens  10  or  less,  monadelphous. 

Seeds  single  in  each  pell,  wingless.  Meliace^,  p.  397. 

Seeds  several  in  each  cell,  winged.  Cedkelaceje,  p.  398. 

Group  10.  Ovary  compound,  or  of  several  carpels  adhering  to  a  central  axis, 
free  from  the  calyx,  which  is  mostly  imbricated  in  aestivation.  Stamens 
as  many  or  twice  as  many  as  the  petals,  inserted  on  the  receptacle,  often 
monadelphous  at  the  base.  Embryo  large.  Albumen  little  or  none. 
Flowers  perfect. 

*  Flower  irregular  and  unsymmetrical.    Albumen  none. 
Stamens  connate.     Ovules  several  in  each  cell.  BALSAMiNACEiE,  p.  400. 

Stamens  distinct.     Ovules  single  in  each  cell.  Trop^olaceje,  p.  400. 

*  *  Flower  regular  and  symmetrical  throughout. 
Leaves  not  glandular-dotted. 

Calyx  valvate.     Albumen  none. 
Calyx  imbricated  in  aestivation. 

Embryo  conduplicate  :  cotyledons  convolute. 
Embryo  straight  or  nearly  so. 

Leaves  entire.    Fertile  stamens  5. 
Leaves  compound.     Stamens  10. 
Styles  separate.     Leaves  alternate. 
Styles  united.     Leaves  opposite. 
Leaves  glandular-dotted. 

Group  11.     Ovary  compound,  with  2 -several  cells  ;  or  one-celled  by  suppres- 
sion ;    or  carpels  distinct  and  barely  connected  by  their  styles.     Calyx 
free.     Petals  as  many  as  the  sepals,  or  rarely  wanting.     Stamens  once  or 
32 


LlMNANTHACE^.,  p. 

401. 

GERANIACEiE,  p. 

399. 

Linages,  p. 

398. 

OXALIDACE^,  p. 

400. 

'ygophyllace^,  p. 

400. 

RuTACEiE,  p. 

401. 

374  EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 

twice  as  many  as  the  sepals,  distinct,  inserted  into  the  receptacle  or  base 
of  the  calyx.  —  Embryo  large  :  albumen  little  or  none.     Flowers  mostly 
dioecious  or  polygamous. 
Leaves  dotted.     Ovaries  or  cells  2-ovuled.  Zanthoxylace^,  p.  401. 

Leaves  dotless.     Ovule  solitary. 

Ovaries  4  or  5,  distinct  in  fruit.  Ochnace^,  p.  402. 

Ovary  one  :  ovule  on  a  long  ascending  funiculus.     Anacardiaceje,  p.  403. 

Group  12.  Ovary  compound,  2-3-lobed,  2-3-celled,  free  from  the  calyx, 
which  is  imbricated  in  aestivation.  Petals  often  irregular,  or  one  fewer 
than  the  sepals,  or  sometimes  wanting.  Stamens  definite,  distinct,  in- 
serted on  or  around  a  hypogynous  disk.  Ovules  1  or  2  in  each  cell. 
Embryo  curved  or  coiled.  Albumen  none.  —  Flowers  often  polygamous. 
Leaves  opposite. 

Entire.     Gynaecium  trimerous.  Malpiguiace^,  p.  404. 

Lobed,  or  compound.     Gynaecium  dimerous.  AceracejE,  p.  404. 

Leaves  chiefly  alternate,     Gynaecium  trimerous.  SAPiNDACEiE,  p.  405. 

Group  13.  Ovary  compound,  2-5-celled.  Calyx  free  from,  or  adherent  to 
the  base  of,  the  ovary.  Petals  and  stamens  equal  in  number  to  the  lobes 
of  the  calyx,  and  inserted  either  into  its  base  or  throat,  or  upon  the  disk 
that  covers  it.  '  Seeds  solitary  or  few  in  each  cell,  albuminous.  Embryo 
mostly  large.  —  Shrubs  or  trees.     Flowers  regular. 

*   Stamens  alternate  with  the  petals. 
Ovaries  partly  separated.     Leaves  compound.  Staphyleaceje,  p.  407. 

Ovaries  wholly  united.    Seed  arillate.    Leaves  simple.   Celastrace.*,  p.  406. 

*  *  Stamens  opposite  the  petals  ! 
Sepals  valvate  in  aestivation.     Cells  1-ovuled.  Rhamnace^e,  p.  406. 

Petals  valvate,  caducous.     Cells  2-ovuled.  Vitaceje,  p.  4U7. 

Group  14.     Ovary  compound,  2-celled,  free  from  the  calyx.     Sepals  and  pet- 
als very  irregular.    Stamens  monadelphous  ;  the  tube  of  filaments  split  on  . 
one  side,  and  more  or  less  united  with  the  claws  of  the  hypogynous  pet- 
als :  the  anthers  one-celled,  and  opening  by  a  pore  at  the  apex !     Seeds 
albuminous.     Embryo  large.  PoLYGALACE^a;,  p.  408. 

Group  15.  Ovary  simple  and  solitary,  free  from  the  calyx;  the  fruit  a  pod. 
Flower  5-merous,  the  odd  sepal  anterior.  Corolla  papilionaceous,  irregu- 
lar, or  sometimes  regular.  Stamens  monadelphous,  diadelphous,  or  dis- 
tinct, mostly  perigynous.     Seeds  destitute  of  albumen. 

Stamens  hypogynous.     Stipules  none.  Krameriace^,  p.  409. 

Stamens  mostly  perigynous.     Fruit  a  legume.  L.eguminos^,  p.  409. 

Group  16.  Ovaries  one  or  several,  simple  and  distinct,  or  combined  into  a 
compound  ovary  with  two  or  more  cells  and  the  placentee  in  the  axis. 
Petals  and  the  distinct  stamens  perigynous.     Seeds  destitute  of  albumen. 

*  Calyx  free,  although  often  inclosing  the  ovaries  in  its  tube,  except  when  the 
latter  are  united,  when  it  is  adnate  to  the  compound  ovary,  and  the  sta- 
mens are  indefinite. 


THE    POLYPETALOTJS    ORDERS.  375 

Leaves  alternate,  stipulate.     Cotyledons  plane.  Rosaceje,  p.  411. 

Leaves  opposite,  exstipulate,  not  dotted.  CALYCANXHACEit,  p.  414. 

Leaves  opposite,  exstipulate,  pellucid-punctuate.  Myrtaceje,  p.  415. 

*  »  Calyx  free  from  the  comp.  ovary.     Stam.  definite.     LvxHRACEiE,  p.  416. 

*  *  *   Calyx-tube  adnate  to  the  compound  ovary.     Stamens  definite. 

Anthers  opening  by  a  pore  at  the  apex.  Melastomace^e,  p.  416. 
Anthers  opening  longitudinally. 

Stipules  interpetiolar.     Leaves  opposite.  Rhizophorace^,  p.  416. 
Stipules  none.     Calyx  valvate. 

Cotyledons  convolute.  CombretacejE,  p.  416. 

Cotyledons  plane.  Onagrace^,  p.  416. 

Group  17.  Ovary  compound,  one-celled,  with  parietal  placentEB.  Petals  and 
(with  one  exception)  stamens  inserted  on  the  throat  of  the  calyx.  Flow- 
ers perfect,  except  in  Papayaceae. 

*  Calyx  adherent  to  the  ovary. 

Albumen  none  or  very  little.  Petals  and  stam.  indefinite.  Cactace^,  p.  418. 
Albumen  very  copious.  Embryo  minute.  Stam.  5.  Grossulace^,  p.  418. 
Albumen  present:  embryo  rather  large.    Stam.  indefinite.    Loasace^,  p.  419. 

*  *   Calyx  free  from  the  ovary. 
Flowers  perfect.     Stamens  5. 

Stamens  distinct,  perigynous.  Turnerace^,  p.  419. 

Stamens  monadelphous,  adnate  to  the  gynophore.    Passifloraceje,  p.  419. 

Flowers  dioecious.     Stamens  10,  on  the  corolla.  Papayace^,  p.  420. 

Group  18.  Ovary  compound,  2-  several-celled  (or  one-celled  by  obliteration) ; 
the  placentae  parietal,  arising  from  the  axis,  but  carried  outwards  to  the 
walls  of  the  pericarp.  Calyx  adnate.  Corolla  frequently  monopetalous. 
Stamens  united  either  by  their  filaments  or  anthers.  Flowers  dioecious 
or  monoecious.     Albumen  none.  CucurbitacejE,  p.  420. 

Group  19.  Ovaries  two  or  more,  many  ovuled,  distinct,  or  partly,  sometimes 
completely,  united,  when  the  compound  ovary  is  one-celled  with  parietal 
placentae,  or  2 -many-celled  with  the  placentae  in  the  axis.  Calyx  either 
free  from  the  ovary,  or  adherent.  Petals  and  stamens  inserted  on  the  ca- 
lyx ;  the  latter  mostly  definite.     Seeds  albuminous,  numerous. 

Pistils  as  many  as  the  sepals.  Crassulace^,  p.  421. 

Pistils  fewer  than  the  sepals,  more  or  less  united.         Saxifragace.«,  p.  422. 

Group  20.  Ovary  compound,  2-  (rarely  3-5-)  celled,  with  a  single  ovule  sus- 
pended from  the  apex  of  each  cell.  Stamens  usually  as  many  as  the  pet- 
als, or  the  lobes  of  the  adherent  calyx.     Embryo  small,  in  hard  albumen. 

«  Summit  of  the  (often  2-lobed)  ovary  free  from  the  calyx;  the  petals  and 
stamens  inserted  on  the  throat  of  the  calyx.  Hamamelace^,  p.  423. 

*  *   Calyx-tube  entirely  adherent  to  the  ovary.     Stamens  and  petals  epigy- 

nous.     Flowers  umbellate. 

Fruit  separable  into  two  dry  carpels.  Umbellifer^,  p.  423. 

Fruit  drupaceous,  usually  of  more  than  two  carpels.  AraliacejE,  p.  425. 

Flowers  cymose  or  capitate.     Drupe  2-celled.  Cornace^e,  p.  425. 


376 


EXOGENOUS    OR    DICOTYLEDONOTTS    PLANTS. 


704.  Ord.  RanunculaceSB  (the  Crowfoot  Family).  Herbaceous, 
occasionally  climbing  plants,  with  an  acrid  watery  juice,  and  usu- 
ally palmately  or  ternately  lobed  or  divided  leaves,  without  stip- 
ules. Calyx  of  three  to  six,  usually  five,  distinct  sepals,  decidu- 
ous, except  in  Pseonia  and  Helleborus.  Petals  five  to  fifteen,  or 
sometimes  none.  Stamens  indefinite,  distinct.  Ovaries  numer- 
ous, rarely  few  or  solitary,  distinct.  Embryo  minute,  at  the  base 
of  firm  albumen  (Fig.  455,  456).  —  Ex.  Ranunculus,  the  Butter- 
cup, which  has  regular  flowers  with  petals.  Clematis  (Virgin's 
Bower),  Anemone,  and  Hepatica  (Liver-leaf),  which  have  no  pet- 
als, but  the  calyx  is  petaloid  :  the  latter  has  an  involucre  entirely 
resembling  a  calyx,  and  the  leaves  of  the  former  are  opposite.  In 
all  these  examples  the  ovaries  are  one-seeded,  and  the  flowers  reg- 
ular. In  others,  the  ovaries  contain  several  seeds,  and  the  flowers 
are  irregular,  or  with  the  petals  in  the  form  of  spurs  or  different 
shaped  bodies.  Actaea  (Cohosh,  Baneberry)  and  one  Larkspur 
have  a  solitary  ovary :  in  the   latter  the  petals  are  consolidated. 


Zanthorhiza  (Yellow-root)  has  only  five  or  ten  stamens.  —  The 


FIG.  476.  Flower  of  a  Ranunculus.  477.  Vertical  section  through  the  receptacle ;  the  se- 
pals, petals,  and  most  of  the  stamens  taken  away.  478.  A  petal,  with  the  nectariferous  scale 
at  its  base.  479.  Section  through  an  ovary,  showmg  the  solitary  ovule  attached  to  the  base  of 
the  cell.  480.  Flower  and  part  of  a  leaf  of  Aquilegia  Canadensis  (Wild  Columbine).  481.  A 
detached  petal.  482.  The  five  carpels  of  the  fruit.  483.  A  separate  follicle.  484.  Vertical 
section  of  the  seed,  showing  the  minute  embryo.  485.  Flower  of  Delphinium,  or  Larkspur, 
with  its  spurred  calyx ;  which  is  removed  in  486,  to  show  the  four  irregular  petals  and  the 
stamens. 


THE    POLYPETALOUS    ORDERS. 


377 


juice  of  all  Ranunculaceous  plants  is  acrid,  or  even  caustic  :  some 
are  virulent  narcotico-acrid  poisons. 

705.  Ord.  Magnoliaceae  (the  Magnolia  Family).  Trees  or  shrubs  ; 
with  ample  and  coriaceous,  alternate,  entire  or  lobed  leaves,  usu- 
ally punctate  with  minute  transparent  dots :  stipules  membrana- 
ceous, enveloping  the  bud,  falling  off  when  the  leaves  expand. 
Flowers  solitary,  large  and  showy,  mostly  odorous.  Calyx  of 
three  to  six  deciduous  sepals,  colored  like  the  petals ;  the  latter 
three  or  several,  often  in  several  rows.  Stamens  numerous,  mostly 
with  short  filaments,  and  adnate  anthers.  Carpels  either  several 
in  a  single  row,  or  numerous  and  spicate  on  the  prolonged  recep- 
tacle ;  in  the  latter  case  usually  more  or  less  cohering  with  each 
other,  and  forming  a  fruit  like  a  cone  or  strobile.  Seeds  mostly 
one  or  two  in  each  carpel^  often  with  a  pulpy  exterior  coat,  and 
suspended,  when  the  carpels  open,  by  an  extensile  funiculus,  com- 
posed of  unrolled  spiral  vessels.  Embryo  minute,  at  the  base  of 
homogeneous  fleshy  albumen.  There  are  three  well-marked  sub- 
orders ;  namely  : 

706.  Subord.  Magnolieac  {tlie  true  Magnolia  Family)^  characterized 


principally  as  above,  especially  by  the  stipules  and  the  imbricated 


FIG.  487.  Magnolia  glauca.  488.  A  stamen,  seen  from  the  inside,  showing  the  two  lobes  of 
the  adnate  anther.  489.  The  carpels  in  fruit,  persistent  on  the  receptacle,  and  opening  by  the 
dorsal  suture ;  the  seeds  suspended  by  their  extensile  cord  of  spiral  vessels, 

32* 


sts 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


spiked  carpels.  —  Ex.  Magnolia,  in  which  the  hard  or  woody  car- 
pels are  persistent,  and  accordingly  open  by  the  dorsal  suture ; 
Liriodendron  (the  White-wood  or  Tulip-tree),  in  which  the  winged 
carpels  fall  away  from  the  receptacle,  but  are  themselves  inde- 
hiscent.     Bitter,  and  somewhat  acrid-aromatic. 

707.  Subord.  WintereSB  {the  Winter's- Bark  Family)  has  no  stip- 
ules, and  the  carpels  occupy  only  a  single  verticil.  These  have 
pungent  aromatic  properties,  as  in  Illicium,  the  Star-Anise,  the 
seeds  and  pods  of  which  furnish  the  aromatic  oil  of  this  name. 

708.  Subord,  SchizandreSB  is  monoecious  or  dioecious,  with  the  pis- 
tils spicate  or  capitate  on  a  prolonged  receptacle ;  the  stamens 
often  monadelphous.  Leaves  sometimes  toothed,  destitute  of  stip- 
ules. —  Ex.  Schizandra.     Mucilaginous,  with  little  aroma. 

709.  Ord.  AaonaceJB    (the    Custard-Apple   Family).      Trees   or 


494  490  491 

shrubs,  with  alternate  entire  leaves,  destitute  of  stipules.     Flowers 


FIG.  490.  Flowering  branch  of  the  Papaw  (Uvaria  triloba)  of  the  natural  size.  491.  The 
receptacle,  with  all  but  the  pistils  removed,  492.  A  stamen,  magnified.  493.  View  of  three 
baccate  pods  from  the  same  receptacle  (much  reduced  in  size)  ;  one  cut  across,  another  length- 
wise, to  show  the  large  bony  seeds.    494.  Section  of  the  seed,  to  show  the  ruminated  albumen. 


THE    POLYPETALOUS    ORDERS.  379 

large,  but  dull  colored.  Sepals  3.  Petals  6,  in  two  rows,  with  a 
valvate  aestivation.  Stamens  numerous,  in  many  rows,  with  ex- 
trorse  anthers.  Carpels  few,  or  mostly  numerous  and  closely 
packed  together,  sometimes  cohering  and  forming  a  fleshy  or  pulpy 
mass  in  the  mature  fruit.  Seeds  one  or  more  in  each  carpel,  with 
a  brittle  testa :  embryo  minute  at  the  base  of  hard,  ruminated  al- 
bumen. Ex.  The  four  species  of  Papaw  (Asimina)  are  our  only 
representatives  of  this  chiefly  tropical  order,  which  furnishes  the 
luscious  Custard-apples  of  the  East  and  West  Indies,  &c.  Ar- 
omatic, and  sometimes  rather  acrid,  properties  prevail  in  the 
order.* 


710.  Ord.  Menispermaceac  (tJie  Moonseed  Family).  Climbing  or 
twining  shrubby  plants  ;  with  alternate  and  simple  palmately-veined 
leaves,  destitute  of  stipules ;  and  small  flowers  in  racemes  or  pani- 
cles, dioecious,  monoecious,  or  polygamous.  Calyx  of  three  to 
twelve  sepals,  in  one  to  three  rows,  deciduous.  Petals  as  many  as 
the  sepals  or  fewer,  small,  or  sometimes  wanting  in  the  pistillate 


*  Ord.  MYRISTICACE^,  consisting  of  a  few  tropical  trees  (which  bear 
nutmegs),  differs  from  Anonacese  in  having  monoecious  or  dioecious  and  apet- 
alous  flowers.  The  aril  and  the  albumen  of  the  seeds  are  fine  aromatics. 
The  common  nutmeg  is  the  seed  of  Myristica  moschata  (a  native  of  the  Mo- 
luccas) deprived  of  the  testa:  mace  is  the  aril  of  the  same  species.  The  ru- 
minated albumen  (627)  is  nearly  peculiar  to  this  family  and  the  Anonaceae. 

FIG.  495.  Staminate  flower  of  Menispermum  Canadense.  496.  A  stamen,  with  its  four- 
lobed  anther.  497.  A  pistillate  flower  of  the  same.  498.  A  solitary  fruit.  499.  Two  drupes 
on  the  same  receptacle,  cut  across  ;  one  through  the  pulpy  exocarp  only,  the  other  through  the 
bony  endocarp  and  seed.  500.  A  drupe  divided  vertically  (the  embryo  here  is  turned  ;,lie  wrong 
way).    501.  The  seed,  and  502,  the  coiled  embryo  detached. 


380 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


flowers.  Stamens  as  many  as  the  petals,  and  opposite  them,  or  two 
to  four  times  as  many  :  anthers  often  four-celled.  Carpels  usually 
several,  but  only  one  or  two  of  them  commonly  fructify,  at  first 
straight,  but  during  their  growth  often  curved  into  a  ring ;  in  fruit 
becoming  berries  or  drupes.  Seeds  solitary,  filling  the  cavity  of 
the  bony  endocarp  :  embryo  large,  inclosed  in  the  thin,  fleshy  al- 
bumen. —  Ex.  Menispermum,  or  Moonseed  (Fig.  495-502),  Coc- 
culus.  The  roots  are  mostly  bitter  and  tonic  (e.  g.  Colombo  Root 
of  the  materia  medica) ;  but  the  fruit  is  often  narcotic  and  acrid  ; 
as,  for  instance,  the  Cocculus  Indicus  of  the  shops,  so  extensively 
used  for  rendering  malt  liquors  more  intoxicating,  and  for  stupefy- 
ing fishes. 

711.  Ord.  Berberidaceac  {the  Barberry  Family).    Herbs  or  shrubs, 


with  a  watery  juice ;  the  leaves  alternate,  compound  or  divided, 


FIG.  503.  A  shoot  of  Berberis  vulgaris,  the  common  Barberry.  504.  A  flowering  branch 
from  the  axil  of  one  of  its  leaves  or  spines  the  following  year.  505.  An  expanded  flower. 
606.  A  petal,  nectariferous  near  the  base.  507.  A  stamen;  the  anther  opening  by  uplifted 
valves.  508.  Cross-section  of  a  young  fruit.  509.  Vertical  section  ;  the  seeds  attached  at  the 
base.  510.  Vertical  section  of  a  seed  enlarged,  showing  the  large  embryo  with  foliaceous  co- 
tyledons and  a  taper  radicle,  surrounded  by  albumen.    511.  The  embryo  separate. 


THE  POLYPETALOUS  ORDERS.  381 

usually  without  stipules.  Flowers  perfect.  Calyx  of  three  to 
nine  sepals,  imbricated,  in  one  to  several  rows,  often  colored. 
Petals  as  many  as  the  sepals  and  in  two  sets,  or  twice  as  many, 
with  a  pore,  spur,  or  glandular  appendage  at  the  base.  Stamens 
equal  in  number  to  the  petals  and  opposite  them,  or  rarely  more 
numerous ;  anthers  extrorse,  the  cells  commonly  opening  by  an 
uplifted  valve.  Carpel  solitary,  often  gibbous  or  oblique,  forming 
a  one-celled  pod  or  berry  in  fruit.  Seeds  sometimes  with  an  aril : 
embryo  (often  minute)  surrounded  with  fleshy  or  horny  albumen. 
—  Ex.  The  Barberry  (Fig.  503-511),  the  sharp  spines  of  which 
are  transformed  leaves  (296)  ;  the  Mahonias  are  Barberries  with 
pinnated  leaves.  Leontice  (Caulophyllum)  thalictroides,  the  Blue 
Cohosh,  is  remarkable  for  its  evanescent  pericarp  (559),  and  the 
consequent  naked  seeds,  which  resemble  drupes.  Podophyllum 
(the  Mandrake)  presents  an  exception  to  the  ordinal  character, 
having  somewhat  numerous  stamens,  with  anthers  which  do  not 
open  by  valves ;  but  the  latter  anomaly  is  also  found  in  Nandina. 
The  order  is  remarkable  for  this  valvular  dehiscence  of  the  an- 
thers, and  for  the  situation  of  both  the  stamens  and  petals  opposite 
the  sepals.  But  this  latter  peculiarity  is  doubtless  owing  to  the 
production  of  two  or  three  whorls  both  of  the  petals  and  the 
stamens,  which  does  away  with  the  anomaly.  The  aestivation 
in  Berberis  clearly  shows  this  to  be  the  case.  The  fruit  is  inno- 
cent or  eatable  ;  the  roots  and  also  the  herbage  sometimes  poi- 
sonous. 

712.  Ord.  Cabombacea;  {the  Water-shield  Family).  Aquatic  herbs, 
with  the  floating  leaves  entire  and  centrally  peltate,  involute  in  ver- 
nation ;  the  submersed  foliage  sometimes  dissected.  Flowers  sol- 
itary, rather  small.  Calyx  of  three  or  four  sepals,  colored  inside, 
persistent.  Corolla  of  as  many  persistent  petals.  Stamens  six  to 
thirty-six,  with  slender  filaments  and  innate  anthers.  Carpels  two 
to  eighteen,  indehiscent,  with  two  or  few  (anatropous)  ovules  in 
each,  inserted  on  the  dorsal  suture  !  Seeds  pendulous,  with  a  mi- 
nute embryo  inclosed  in  a  membranous  bag  (the  persistent  em- 
bryo-sac, 575),  which  is  half  immersed  in  the  albumen  at  the  ex- 
tremity next  the  hilum.  —  Ex.  Brasenia,  the  Water-shield  (Fig. 
512),  and  Cabomba,  compose  this  very  small  order;  the  appar- 
ently single  species  of  the  former  grows  both  in  the  United  States 
and  in  New  Holland.  They  are  only  reduced  forms  of  Nymphse- 
acese. 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


713.  Ord.  Nelumbiacea;  {the  Nelumho  Family).  Aquatic  herbs, 
with  very  large  leaves  and  flowers,  on  long  stalks  arising  from  a 
prostrate  trunk  or  rhizoma,  which  has  a  somewhat  milky  juice  : 
the  leaves  orbicular  and  centrally  peltate.  Calyx  of  four  or  five 
sepals,  deciduous.  Petals  numerous,  inserted  in  several  rows  into 
the  base  of  a  large  and  fleshy  obconical  torus,  deciduous.  Sta- 
mens inserted  into  the  torus  in  several  rows :  the  filaments  peta- 
loid  ;  the  anthers  adnate  and  introrse.  Carpels  several,  separately 
immersed  in  hollows  of  the  enlarged  flat-topped  torus  or  recepta- 
cle (Fig.  351),  each  containing  a  single  anatropous  ovule  ;  in  fruit 
forming  hard,  round  nuts.  Seed  without  albumen  :  embryo  very- 
large,  with  two  fleshy  cotyledons,  and  a  highly  developed  plumule. 
—  Ex.  The  order  consists  of  the  single  genus  Nelumbium,  em- 
bracing two  species ;  one  a  native  of  Asia,  the  other  of  the  United 


FIG.  512.  Brasenia  peltata  (Water-shield) ;  the  lower  flower  with  the  floral  envelopes  and  a 
part  of  the  stamens  removed.  513.  A  magnified  stamen.  514.  A  magnified  carpel.  515.  The 
same  divided  lengthwise,  showing  the  ovules  attached  to  the  outer  or  dorsal  suture  !  516.  Sec- 
lion  of  a  carpel,  in  fruit.  517.  A  magnified  seed,  with  half  the  outer  integument  removed,  dis- 
playing at  the  upper  extremity  the  bag  which  contains  the  embryo.  518.  A  magnified  section 
through  the  middle  of  the  albumen,  &c. ;  bringing  to  view  the  minute  embryo  inclosed  in  its 
BBC,  lying  outside  of  the  albumen,  which  forms  the  principal  bulk  of  the  seed. 


THE  POLYPETALOUS  ORDERS.  383 

States.      They  are  chiefly  remarkable  for  their  very  large  and 
showy  leaves  and  flowers.     The  nuts  are  eatable. 

714.  Ord.  NympllSCacea;  {the  Water- Lily  Family).  Aquatic  herbs, 
with  showy  flowers,  and  cordate  or  peltate  leaves  arising  from  a 
prostrate  trunk  or  rhizoma,  and  raised  on  long  stalks  above  the 
water,  or  floating  on  its  surface.  Calyx  and  corolla  of  several  or 
numerous  imbricated  sepals  and  petals,  which  gradually  pass  into 
each  other ;  persistent ;  the  latter  inserted  on  the  fleshy  torus' 
which  surrounds  or  partly  incloses  and  adheres  to  the  pistil ;  the 
inner  series  gradually  changing  into  stamens.  Stamens  numer- 
ous, in  several  rows,  inserted  into  the  torus  with  or  above  the  pet- 
als ;  many  of  the  filaments  petaloid,  the  adnate  anthers  introrse. 
Fruit  indehiscent,  pulpy  when  ripe,  many-celled,  crowned  with  the 
radiate  stigmas ;  the  anatropous  seeds  covering  the  spongy  dissep- 
iments. Embryo  small,  inclosed  in  a  membranous  bag,  which  is 
situated  next  the  hilum,  and  half  immersed  in  the  mealy  albumen. 
^Ex.  Nymphsea,  the  White  Water-Lily  (Fig.  265-268);  Nu- 
phar,  the  Yellow  Pond-Lily.  Here  belongs  the  magnificent  Vic- 
toria of  tropical  South  America,  the  most  gigantic  and  showy  of 
aquatics,  both  as  to  its  flowers  and  its  leaves. 

715.  Ord,  SarraceniaceBB  (the  Water- Pitcher  Family).  Perennial 
herbs,  growing  in  bogs;  the  (purplish  or  yellowish-green)  leaves  all 
radical  and  hollow,  pitcher-shaped  (Fig.  223,  224),  or  trumpet- 
shaped.  Flower  solitary  on  a  long  scape.  Calyx  of  five  persist- 
ent sepals,  with  three  small  bracts  at  its  base.  Corolla  of  five 
petals.  Stamens  numerous.  Summit  of  the  combined  styles  very 
large  and  petaloid,  five-angled,  covering  the  five-celled  ovary,  per- 
sistent. Fruit  five-celled,  five-valved,  with  a  large  placenta  pro- 
jecting from  the  axis  into  the  cells.  Seeds  numerous,  albuminous, 
with  a  small  embryo.  —  Ex,  Sarracenia,  from  which  the  above 
character  is  taken,  was  the  only  known  genus  of  the  order,  until 
the  recent  discovery  of  Heliamphora  in  Guiana.  The  scape  of  the 
latter  bears  several  flowers  without  petals,  &c.  The  species  of 
Sarracenia  are  all  North  American,  and,  excepting  S.  purpurea, 
are  confined  to  the  Southern  States  east  of  the  AUeghanies. 

716.  Ord.  Papavcraceae  {the  Poppy  Family).  Herbs,  with  a  milky 
or  colored  juice,  and  alternate  leaves  without  stipules.  Calyx  of 
two  (rarely  three)  caducous  sepals.  Corolla  of  four  to  six  regular 
petals.  Stamens  eight  to  twenty-four,  or  numerous.  Fruit  one- 
celled,  either  pod-shaped  with  two  to  five,  or  capsular  with  numer- 


384 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


ous  parietal  placentee,  from  which  the  valves  often  separate  in  de- 
hiscence. Seeds  numerous,  with  a  minute  embryo,  and  copious 
fleshy  and  oily  albumen.  —  Ex.  The  Poppy  (Papaver),  the  leading 
representative  of  this  small  but  important  family,  is  remarkable  for 
the  extension  of  the  placentae  so  as  nearly  to  divide  the  cavity  of 
the  ovary  into  several  cells,  and  for  the  dehiscence  of  the  capsule 


by  mere  chinks  or  pores  under  the  edge  of  the  crown  formed  by 
the  radiate  stigmas.  The  Eschscholtzia,  now  common  in  gardens, 
is  remarkable  for  the  expanded  apex  of  the  peduncle,  and  for  the 
union  of  the  two  sepals  into  a  cahjptra,  like  a  candle-extinguisher, 
which,  separating  at  the  base,  is  thrown  off  by  the  expansion  of 
the  petals  (Fig.  522,  523).  The  colored  juice  is  narcotic  and 
stimulant.  That  of  the  Poppy  yields  opium.  The  colored  juice  of 
the  Celandine,  and  of  the  Bloodroot  (Sanguinaria,  Fig.  519),  is 
acrid. 

FIG.  519.  Sanguinaria  Canadensis  (the  Bloodroot).  520.  The  pod,  divided  transversely, 
showing  the  parietal  attachment  of  the  seeds.  521.  Longitudinal  section  of  a  magnified  seed 
with  its  large  raphe,  showing  the  minute  embryo,  near  the  extremity  of  the  albumen. 
522  Flower-bud  of  Eschscholtzia.  523.  The  calyptriform  calyx  detached  from*  the  base. 
524.  Pod  of  the  same. 


THE  POLYPETALOUS  ORDERS.  385 

717.  Ord.  FumariaceSB  {the  Fumitory  Family),  Smooth  herbs, 
with  brittle  stems,  and  a  watery  juice,  alternate  dissected  leaves, 
and  no  stipules.  Flowers  irregular.  Calyx  of  two  sepals.  Co- 
rolla of  four  petals,  in  pairs  ;  the  two  outer,  or  one  of  them,  spurred 
or  sac-like  at  the  base ;  the  two  inner  callous  and  cohering  at 
the  apex,  including  the  anthers  and  stigma.  Stamens  six,  in  two 
parcels  opposite  the  outer  petals ;  the  filaments  of  each  set  usually 
more  or  less  united ;  the  middle  one  bearing  a  two-celled  anther  ; 
the  lateral  with  one-celled  or  half-anthers.  Fruit  a  one-celled  and 
tvvo-valved  pod,  or  round  and  indehiscent.  Seeds  with  fleshy  al- 
bumen and  a  small  embryo.  —  Ex.  Fumaria,  Dicentra,  Corydalis. 
A  small  and  unimportant  tribe  of  plants,  chiefly  remarkable  for 
their  singular  irregular  flowers  ;  by  which  alone  they  are  distin- 
guished, and  that  not  very  definitely,  from  the  preceding  fam- 
ily. Its  floral  structure  has  already  been  explained  (455,  Fig. 
294-299). 

718.  Ord.  Crucifera;  {the  Mmtard  Family).  Herbs,  with  a  pun- 
gent or  acrid  watery  juice,  and  alternate  leaves  without  stipules  ; 
the  flowers  in  racemes  or  corymbs,  with  no  bracts  to  the  pedicels. 
Calyx  of  four  sepals,  deciduous.  Corolla  of  four  regular  petals, 
with  claws,  their  spreading  limbs  forming  a  cross.  Stamens  six, 
two  of  them  shorter  {tetradynamous^  519).  Fruit  a  pod  (called  a 
silique  when  much  longer  than  broad,  or  a  silicle  when  short,  615), 
which  is  two-celled  by  a  membranous  partition  that  unites  the  two 
marginal  placentae,  from  which  the  two  valves  usually  fall  away. 
Seeds  with  no  albumen  :  embryo  with  the  cotyledons  folded  on  the 
radicle.  —  Ex.  The  Water-Cress,  Radish,  Mustard,  Cabbage,  &c. 
A  very  natural  order,  found  in  every  part  of  the  world,  perfectly 
distinguished  by  having  six  tetradynamous  stamens  along  with  four 
petals  and  four  sepals,  and  by  the  peculiar  pod.  The  peculiarity 
of  the  stamens  is  explained,  and  the  symmetry  of  the  flower  shown, 
on  p.  250.  These  plants  have  a  peculiar  volatile  acridity  (and 
often  an  ethereal  oil,  which  abounds  in  sulphur)  dispersed  through 
every  part,  from  which  they  derive  their  peculiar  odor  and  sharp 
taste,  and  their  stimulant,  rubefacient,  and  antiscorbutic  properties. 
The  roots  of  some  perennial  species,  such  as  the  Horseradish,  or 
the  seeds  of  annual  species,  as  the  Mustard,  are  used  as  condi- 
ments. In  some  cultivated  plants,  the  acrid  principle  is  dispersed 
among  abundance  of  saccharine  and  mucilaginous  matter,  afford- 
ing wholesome  food  ;  as  the  root  of  the  Turnip  and  Radish ;  the 

33 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


leaves,  &c.,  of  the  Cabbage  and  Cauliflower.  None  are  really 
poisonous  plants,  although  some  are  very  acrid.  Several  species 
are  in  cultivation,  for  their  beauty  or  fragrance  ;  such  as  the  Wall- 
flower and  Stock,  &c. 


719.  Ord.  CapparidaceSB  (the  Caper  Family).  Herbs,  or  in  the 
tropics  often  shrubs  or  trees ;  differing  from  Cruciferse  in  the  one- 
celled  pod  (which  is  often  stalked)  being  destitute  of  any  false  par- 
tition ;  in  the  kidney-shaped  seeds ;  and  in  the  stamens,  which, 
when  six,  are  scarcely  tetradynamous,  and  are  often  more  numer- 
ous. —  Ex'.  Cleome,  and  Polanisia  (Fig.  525-534)  ;  chiefly  tropi- 
cal or  subtropical.  Many  have  the  pungency  of  Cruciferse,  but 
are  more  acrid.     Capers  are  the  pickled  flower-buds  of  Capparis 


FIG.  525.  A  Cruciferous  flower.  526.  The  same,  with  the  calyx  and  corolla  removed,  show- 
ing the  tetradynamous  stamens.  527.  /S'lVt^Mes  of  A  rabi  3  Canadensis;  one  of  Ihem  with  one  of 
the  valves  detached,  showing  the  seeds  lying  on  the  false  partition;  the  other  valve  also  falling 
away.  523,  A  magnified  cross-section  of  one  of  the  winged  seeds,  showing  the  embryo  with 
the  radicle  applied  to  the  edge  of  the  cotyledons  (cotyledons  accumbent).  529.  The  embryo 
detached.  530.  The  raceme  of  Draba  verna,  in  fruit.  531.  A  cross-section  of  one  of  the  sili- 
cles,  magnified,  exhibiting  the  parietal  insertion  of  the  seeds,  and  the  false  partition.  532.  A 
silicle  of  Shepherd's  Purse  (Capsella  Bursa  Pastoris).  533.  The  same,  with  one  of  the  boat- 
shaped  valves  removed,  presenting  a  longitudinal  view  of  the  narrow  partition,  &c.  534.  A 
magnified  cross-section  of  one  of  the  seeds,  showing  the  embryo  with  the  radicle  applied  to  the 
side  of  the  cotyledon  (cotyledons  incumbent). 


THE    POLYPETALOUS    ORDERS. 


387 


spinosa  of  the  Levant,  &c.     The  roots  and  herbage  or  bark  are 
bitter,  nauseous,  and  sometimes  poisonous. 


720.  Ord.  Ressdacese  {the  Mignonette  Family).  Herbs,  with  a 
watery  juice,  and  alternate  leaves  without  stipules,  except  a  pair  of 
glands  be  so  considered :  the  flowers  in  terminal  racemes,  small, 
and  often  fragrant.  —  Calyx  persistent,  of  four  to  seven  sepals, 
somewhat  united  at  the  base.  Corolla  of  two  to  seven  usually  un- 
equal and  lacerated  petals,  with  J)road  or  thickened  nectariferous 
claws.  A  fleshy  disk  is  commonly  present,  enlarged  posteriorly 
between  the  petals  and  the  stamens,  and  bearing  the  latter,  which 
vary  from  three  to  forty  in  number,  and  are  not  covered  by  the 
petals  in  the  bud.  Fruit  a  one-celled  pod,  with  three  to  six  parie- 
tal placentse,  three  to  six-lobed  at  the  apex,  where  it  opens  along 
the  inner  sutures,  usually  long  before  the  seeds  are  ripe.  Seeds 
several  or  many,  curved  or  kidney-shaped,  with  no  albumen  ;  the 
embryo  incurved.  —  Ex.  The  common  representative  of  this  order 
is  the  Mignonette  (Reseda  odorata),  prized  for  its  fragrant  flowers. 

721.  Ord.  YiolaceSB  {the  Violet  Family).  Herbs  (in  tropical  coun- 
tries sometimes  shrubby  plants),  with  mostly  alternate  simple 
leaves,  on  petioles,  furnished  with  stipules ;  and  irregular  flowers. 
Calyx  of  five  persistent  sepals,  often  auricled  at  the  base.  Corolla 
of  five  unequal  petals,  one  of  them  larger  than  the  others  and  com- 

FIG.  535.  Flower  of  Polanisia  graveolens.  536  Fructified  ovary  of  the  same,  a  portion  cut 
away  by  a  vertical  and  horizontal  section,  to  show  the  single  cell  and  two  parietal  placentse. 
537.  Cross-section  of  the  ovary.  538.  Sectionof  the  seed  and  embryo.  539.  Flower  of  Gynan- 
dropsis. 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

monly  bearing  a  spur  or  sac  at  the  base :  aestivation  imbricative. 
Stamens  five,  with  short  and  broad  filaments,  which  are  usually- 
elongated  beyond  the  (adnate  introrse)  anthers;  two  of  them  com- 
monly bearing  a  gland  or  a  slender  appendage  which  is  concealed 
in  the  spur  of  the  corolla  :  the  anthers  approaching  each  other,  or 
united  in  a  ring  or  tube.  Style  usually  turned  to  one  side,  and 
thickened  or  hooded  at  the  apex.  Fruit  a  one-celled  capsule, 
opening  by  three  valves,  each  valve  bearing  a  parietal  placentae  on 
its  middle.  Seeds  several  or  numerous,  anatropous,  with  a  crusta- 
ceous  integument.  Embryo  straight,  nearly  the  length  of  the 
fleshy  albumen. —  Ex.  The  Violet  (Viola)  is  the  type  and  principal 


genus  of  this  order ;  some  species,  like  the  Pansy,  are  cultivated 
for  the  beauty  of  their  flowers ;  others  for  their  delicate  fragrance. 
The  roots  of  all  are  acrid. 

722.  Ord.  DroseraceSB  (the  Sundeio  Family).  Small  herbs,  grow- 
ing in  swamps,  usually  covered  with  gland-bearing  hairs ;  with  the 
leaves  alternate,  or  clustered  at  the  base  of  a  scape,  tapering  into  a 
petiole,  rolled  up  from  the  apex  to  the  base  in  vernation  (circin- 
nate) :  stipules  none,  except  a  fringe  of  hairs  or  bristles  at  the  base 
of  the   petioles.     Calyx  of  five  equal  sepals,  persistent.     Corolla 

FIG.  540.  Viola  sag!  ttata.  541.  One  of  the  stamens  without  appendage,  seen  from  within; 
and  one  furnished  with  a  spur-like  appendage  on  the  back.  542.  A  capsule  which  has  opened 
and  separated  into  three  valves ;  the  calyx  still  persistent.  543.  A  valve  of  the  same,  from 
which  the  seeds  have  fallen.  544.  A  magnified  seed.  545.  The  same  divided  vertically,  show- 
ing the  large  embryo  in  the  midst  of  albumen. 


THE  POLYPETALOUS  ORDERS.  389 

of  five  regular  petals,  withering  and  persistent,  convolute  in  aestiva- 
tion. Stamens  as  many  as  the  petals  and  alternate  with  them,  or 
sometimes  two  to  three  times  as  many,  distinct,  withering ;  anthers 
extrorse.  Styles  three  to  five,  distinct  or  nearly  so,  and  each  two- 
parted  (so  as  to  be  taken  for  ten  styles,  Fig.  390),  with  the  divis- 
ions sometimes  two-lobed  or  many-cleft  at  the  apex ;  sometimes 
all  united  into  one.  Fruit  a  one-celled  capsule,  opening  loculici- 
dally  by  three  to  five  valves,  with  three  to  five  parietal  placentae ; 
in  Dionsea  membranaceous  and  bursting  irregularly,  with  a  thick 
placenta  at  the  base.  Seeds  usually  numerous.  Embryo  small, 
at  the  base  of  cartilaginous  or  fleshy  albumen.  —  Ex.  Drosera,  the 
Sundew;  and  Dionsea  (Fig.  228),  so  remarkable  for  its  sensitive 
leaves,  which  suddenly  close  when  touched. 

723.  Subord.  ParnassieaB  consists  of  the  genus  Parnassia  (belong- 
ing to  the  northern  temperate  and  frigid  zones,  and  to  the  high 
mountains  of  tropical  Asia) ;  which  differs  from  Droseraceae  in  the 
want  of  glandular  hairs,  in  the  introrse  anthers,  exalbuminous 
seeds,  imbricated  aestivation  of  the  petals,  and  curious  appendages 
before  each  petal.  These  are  explained,  and  the  plan  of  the  flower 
shown,  on  p.  253  (Fig.  304,  305).  In  the  ovary,  also,  the  four 
short  stigmas  are  situated  opposite  the  four  parietal  placentae. 
The  genus  has  been  placed  in  Saxifragacese  on  account  of  its 
slightly  perigynous  stamens,  &c.,  and  in  Hypericaceae  on  account 
of  the  sterile  stamens  in  five  sets,  and  the  absence  of  albumen 
in  the  seeds. 

7'Z4.  Ord.  Cistacese  {the  Rock-Rose  Family).  Low  shrubby  plants 
or  herbs,  with  simple  and  entire  leaves  (at  least  the  lower  oppo- 
site). Calyx  of  five  persistent  sepals,  the  three  inner  with  a  con- 
volute aestivation  ;  the  two  outer  small  or  sometimes  wanting.  Co- 
rolla of  five,  or  rarely  three,  regular  petals,  convolute  in  aestivation 
in  the  direction  contrary  to  that  of  the  sepals,  often  crumpled,  usu- 
ally ephemeral,  sometimes  wanting,  at  least  in  a  portion  of  the 
flowers.  Stamens  few  or  numerous,  distinct,  with  short  innate 
anthers.  Fruit  a  one-celled  capsule  with  parietal  placentae,  or  im- 
perfectly three  to  five-celled  by  dissepiments  arising  from  the  mid- 
dle of  the  valves  (dehiscence  therefore  loculicidal),  and  bearing 
the  placentae  at  or  near  the  axis.  Seeds  few  or  numerous,  ortho- 
tropous  (with  few  exceptions),  with  mealy  albumen.  Embryo 
curved,  or  variously  coiled  or  bent.  —  Ex.  Cistus,  Helianthemum 
(Fig.  546) :  a  small  family ;  the  flowers  often  showy.  No  im- 
33* 


S90 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


portant  properties.    Several  exude  a  balsamic  resin,  such  as  Lada- 
num  from  a  Cistus  of  the  Levant.* 


725.  Ord.  HypericaceaB  {the  St.  John's-wort  Family).  Shrubs  or 
herbs,  with  a  resinous  or  limpid  juice,  and  opposite  entire  leaves, 
destitute  of  stipules,  and  punctate  with  pellucid  or  blackish  dots. 
Flowers  regular.  Calyx  of  four  or  five  persistent  sepals,  the  two 
exterior  often  smaller.  Petals  four  or  five,  twisted  in  aestivation, 
often  with  black  dots.  Stamens  commonly  polyadelphous  and  nu- 
merous. Capsule  with  septicidal  dehiscence,  many-seeded.  — 
Ex.  Hypericum  (St.  John's- wort,  Fig.  553)  is  the  type  of  this 
small  family.  The  plants  yield  a  resinous  acid  juice,  and  a  bitter, 
balsamic  extractive  matter.t     Embryo  straight ;   albumen  little  or 


*  Ord,  BIXACEiE  consists  of  tropical  trees  or  shrubs,  not  resembling  any 
of  the  other  orders  with  parietal  placentae,  and  is  here  mentioned  because 
Bixa  Orellana,  of  tropical  America,  yields  the  Arnotto  of  commerce;  which 
is  the  waxy,  orange-red  pulp  that  surrounds  the  seeds,  and  is  separated  from 
them  by  washing.  It  is  chiefly  used  for  staining  cheese,  and  in  the  prepara- 
tion of  chocolate. 

t  Ord.  GUTTIFERiE,  or  CLUSIACE^,  consisting  of  tropical  trees, 
with  a  yellow,  resinous  juice,  large  flowers,  and  thick  and  shining  entire 
leaves,  is  nearly  allied  to  Hypericaceoe,  and  exhibits  the  acrid  properties  of  the 
latter  family  in  a  much  higher  degree.  —  Gamboge  is  the  hardened  resinous 

FIG.  546.  The  Rock-Rose,  Helianthemum  Canadense.  547.  Flower  from  which  the  petals 
and  stamens  have  fallen.  548.  Magnified  cross-section  of  the  ovary ;  with  a  single  stamen, 
showing  its  hypogynoua  insertion.  549.  Cross-section  of  a  capsule,  loculicidally  dehiscent ; 
the  seeds  therefore  borne  on  the  middle  of  each  valve.  550.  An  ovule.  551.  Plan  of  the  flower. 
552.  Section  of  a  seed,  showing  the  curved  embryo. 


THE    POLYPETALOUS    ORDERS. 


391 


none.     The  peculiarity  of  the  stamens  is  explained,  and  a  diagram 
of  the  flower  of  Elodea  is  given,  on  p.  252. 


726.  Ord.  Elatinacese  {the  Watenvort  Family).  Small. annual 
weeds,  with  opposite  leaves,  membranaceous  stipules,  and  minute 
axillary  flowers.  Sepals  and  petals  three  to  five.  Stamens  as 
many  or  twice  as  many  as  the  petals,  distinct.  Capsule  2-5- 
celled,  septicidal  or  septifragal ;  the  numerous  seeds  attached  to  a 
persistent  central  axis.  Albumen  none.  —  Ex.  Elatine  is  the  type 
of  this  order,  containing  a  few  insignificant  weeds. 

727.  Ord,  CaryophyllaceSB  {the  Pink  Family).  Herbs,  with  oppo- 
site entire  leaves  ;  the  stems  tumid  at  the  nodes.  Flowers  regular. 
Calyx  of  four  or  five  sepals.  Corolla  of  four  or  five  petals,  or 
sometimes  wanting.     Stamens  as  many,  or  commonly  twice  as 


juice  of  the  Hebradendron  cambogioides  of  Ceylon  ;  but  the  tree  is  supposed 
to  have  been  imported  from  Siam  by  the  Buddhists,  to  whom  it  is  sacred,  on 
account  of  the  yellow  color  it  yields.  The  gamboge  from  Siam  forms  the 
best  pigment.  Clusia  flava  yields  the  Hog-gum,  of  Jamaica.  The  hot  aro- 
matic Canella  bark,  or  False  Winter  s-bark,  is  derived  from  the  Canella  alba 
of  the  West  Indies.  Notwithstanding  the  acrid  properties  of  this  order,  Gar- 
cinia  Mangostana  of  Malacca  yields  one  of  the  most  delicious  of  fruits,  the 
Mangosteen. 

Ord,  TAMARISCINEJE  consists  of  Tamarix  and  one  or  two  other  gen- 
era of  sea-side  plants,  natives  of  Europe  and  Asia  :  they  are  ornamental, 
shrubby  plants,  with  small  scale-like  and  somewhat  fleshy  leaves,  and  an  as- 
tringent bark. 


FIG.  553.    Hypericum  perforatum  (St.  John'swort).     554.    Its  tricarpellary  pistil. 
Cross-section  of  the  capsule.    556,  Vertical  section  of  a  seed  and  its  embryo. 


555. 


392 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


many,  as  the  petals,  sometimes  reduced  to  two  or  three.  Styles 
two  to  five,  stigmatose  down  the  inside.  Ovary  mostly  one-celled, 
with  a  central  or  basilar  placenta.  Capsule  two  to  five-valved,  or 
opening  only  at  the  apex  with  twice  as  many  valves  as  stigmas. 
Embryo  peripheric,  curved  or  coiled  around  the  outside  of  mealy 
albumen.  —  There  are  five  principal  suborders,  viz. :  — 

728.  Subord.  SileneSB  {the  proper  Pink  Family)  :  in  which  the 
sepals  are  united  into  a  tube,  and  the  petals  (mostly  convolute  in 
aestivation)  and  stamens  are  inserted  on  the  stipe  of  the  ovary,  the 
former  with  long  claws  ;  and  there  are  no  stipules.  —  Ex.  Silene, 
Dianthus  (the  Pink,  Carnation). 

729.  Subord.  Alsinese  {the  Chickweed  Family) ;  in  which  there  are 

no  stipules,  the  ovary 
is  sessile,  the  sepals 
and  petals  (imbricat- 
ed in  aestivation)  are 
nearly  or  quite  dis- 
tinct ;  the  petals  des- 
titute of  claws ;  and 
the  stamens  are  in- 
serted into  the  margin 
of  a  small  hypogynous 
disk,  which,  however, 
occasionally  coheres 
with  the  base  of  the  ca- 
lyx, and  becomes  peri- 
gynous.  —  Ex.  Stel- 
laria,  Arenaria,  &c. 
(Chickweeds).  Some 
are  ornamental;  oth- 
ers, such  as  the  common  Chickweed,  are  insignificant  weeds. 

730.  Subord.  lUecebreSB  {the  Knotwort  Family) ;  difl!ering  from  the 
last  in  having  scarious  stipules ;  the  sepals  often  united  below  ;  the 
petals  often  wanting  or  rudimentary ;  the  stamens  manifestly  peri- 
gynous,  and  the  fruit  more  commonly  a  one-seeded  utricle.  —  Ex. 
Paronychia  and  Anychia,  Spergula  has  conspicuous  petals,  and 
many-seeded  capsules;  and  so  differs  from  Alsineae  only  in  its 
stipules.     Insignificant  weeds  of  no  economical  account. 


FIG.  557.  Arenaria  lateriflora.  55S.  A  magnified  flower.  559.  Magnified  section  of  a  seed, 
showing  the  embryo  coiled  into  a  ring  around  the  albumen.  560.  Vertical  section  of  a  pistil  of 
Spergularia. 


THE  POLYPETALOUS  ORDERS. 


393 


731.  Subord.  SclerantheiB  {the  Knawel  Family)  is  like  the  last, 
only  there  are  no  stipules,  and  the  calyx-tube  is  urceolate  in  fruit, 
inclosing  the  utricle.  —  Ex.  Scleranthus. 

732.  Subord.  MoUugiliese  {the  Carpet-weed  Family),  is  apetalous, 
exstipulate,  and  has  the  stamens  alternate  with  the  sepals  when  of 
the  same  number;  thus  effecting  a  transition  to  the  next  order. — 
Ex.  MoUugo. 

733.  Ord.  PortulacaceSB  {the  Purslane  Family).  Succulent  or 
fleshy  herbs,  with  alternate  or  opposite  entire  leaves,  destitute  of 
proper  stipules,  and  usually  ephemeral  flowers.  Calyx  mosdy  of 
two  or  three  sepals,  cohering  with  the  base  of  the  ovary.  Petals 
five,  or  rarely  more  numerous.  Stamens  variable  in  number,  but 
when  equal  to  the  petals  situated  opposite  them.  Styles  two  to 
eight,  united  below.  Capsule  with  few  or  numerous  seeds,  attach- 
ed to  a  central  basilar  placenta,  often  by  slender  funiculi.  Seed 
and  embryo  as  in  Caryophyllacese.  —  Ex.  Portulaca  (Purslane), 


Claytonia  (Fig.  561).     Chiefly  natives  of  dry  and  arid  places  in 


FIG.  561,  Claytonia  Virginica  (Spring  Beauty).  562.  Young  fruit  and  the  persistent  two- 
leaved  calyx.  563.  Section  of  the  dehiscing  capsule.  664.  A  seed.  565,  The  same,  vertically 
divided.     566.  The  embryo  detached. 

FIG.  567.  Flower  of  the  Purslane  ;  the  calyx  cut  away  at  the  point  where  it  adheres  to  the 
ovary,  and  laid  open.    568.  A  capsule  (pyxis,  616)  of  the  same,  transversely  dehiscent. 


3d4.  EXOGENOUS    OR    DICOTYLEDONOUS   PLANTS. 

the  warmer  parts  of  the  world ;  except  Claytonia.  Insipid  or 
slightly  bitter:  several  are  used  as  pot-herbs,  as  the  Purslane. 
Some  are  ornamental.  The  farinaceous  root  of  Lewisia  rediviva, 
a  native  of  dry  plains  in  the  interior  of  Oregon,  is  an  important 
article  of  food  with  the  natives. 

739.  Ord.  Mesembryanthemacese  {the  Fig-Marigold  Family).  Con- 
sists of  succulent  plants,  with  showy  flowers  opening  only  under 
bright  sunshine,  containing  an  indefinite  number  of  petals  and  sta- 
mens, and  a  many -celled  and  many-seeded  capsule ;  otherwise 
much  as  in  Caryophyllacese,  —  The  thickened  leaves  are  often 
oddly  shaped.  —  Ex.  Mesembryanthemum  (Fig-Marigold,  Ice- 
plant)  ;  the  numerous  species  are  chiefly  natives  of  the  Cape  of 
Good  Hope,  flourishing  in  the  most  arid  situations. 

740.  Ord.  Malvaceae  {the  Mallow  Family).  Herbs,  shrubs,  or 
rarely  trees.  Leaves  alternate,  palmately  veined,  furnished  with 
stipules.  Flowers  regular,  generally  showy,  often  with  an  involu- 
cel,  forming  a  double  calyx.  Calyx  mostly  of  five  sepals,  more 
or  less  united  at  the  base,  valvate  in  asstivation.  Petals  as  many 
as  the  sepals,  convolute  in  lestivation,  hypogynous.  Stamens  in- 
definite, monadelphous ;  inserted  with  the  petals,  united  with  their 
claws  :  anthers  reniform,  one-celled.  Pollen  hispid.  Ovary  sev- 
eral-celled, with  the  placentae  in  the  axis ;  or  ovaries  several,  sep- 
arate or  separable  at  maturity.  Styles  as  many  as  the  carpels, 
distinct  or  united  below.  Fruit  capsular,  or  the  carpels  separate 
or  separable.     Seeds  with  little  mucilaginous  or  fleshy  albumen. 


Embryo  large,  with  foliaceous  cotyledons,  variously  incurved  or 

FIG.  617.  The  Marsh  Mallow  (Althaea  officinalis).  618.  One  of  the  kidney-shaped  one- 
celled  anthers,  magnified.  619.  The  pistils,  magnified.  620.  Capsule  of  Hibiscus  Moscheutos, 
with  the  persistent  calyx  and  involucel.    621.  The  same,  loculicidally  dehiscent. 


THE  POLYPETALOirS  ORDERS.  395 

folded. —  Ex.  Malva  (Mallows),  Althaea  (Hollyhock),  Gossypium 
(Cotton),  &c. :  a  pretty  large  and  important  family.  Malvaceous 
plants  commonly  abound  in  mucilage,  and  are  entirely  destitute  of 
unwholesome  qualities.  The  unripe  fruit  of  Hibiscus  esculentus 
(Okra)  is  used  as  an  ingredient  in  soups.  Althaea  officinalis  is  the 
Marsh  Mallow  of  Europe,  the  Guimauve  of  the  French.  The 
tenacious  inner  bark  of  many  species  is  employed  for  cordage. 
Cotton  is  the  hairy  covering  of  the  seeds  of  Gossypium  :  the  long 
and  slender  tubes,  or  attenuated  cells,  collapse  and  twist  spirally 
as  the  seed  ripens,  which  renders  the  substance  capable  of  being 
spun.  Cotton-seed  yields  a  fixed  oil  in  large  quanthy,  which  may 
be  used  for  lamps,  &c.  Numerous  species  are  cultivated  for  orna- 
ment. 

741.  Ord.  ByttneriaceJB  is  distinguished  from  the  foregoing  by  its 
usually  definite  stamens,  and  the  two-celled  anthers  (the  cells  par- 
allel), with  smooth  pollen.  The  carpels  are  few  and  consolidated. 
—  A  Melochia  and  a  Hermannia  are  found  in  Texas.  The  rest  of 
the  order  is  tropical  or  subtropical.  Chocolate  is  made  of  the 
roasted  and  comminuted  seeds  of  Theobroma  Cacao  (a  South 
American  tree),  mixed  with  sugar,  arnotto,  vanilla,  and  other  in- 
gredients, and  pressed  into  cakes.  The  roasted  integuments  of  the 
seeds,  also,  are  used  as  a  substitute  for  coffee.* 

742.  Ord.  TiliaceSB  (the  Linden  Family).  Trees  or  shrubby 
plants,  with  alternate  leaves,  furnished  with  deciduous  stipules,  and 
small  flowers.  Calyx  deciduous.  Petals  sometimes  imbricated  in 
aestivation.     Disk  glandular.     Stamens  indefinite,  often  in  three  to 

*  Ord.  STERCULIACE^,  very  closely  allied  to  Malvacese  and  Byttne- 
riacesB,  and  consisting  of  tropical  trees,  possesses  the  same  mucilaginous  prop- 
erties (as  well  as  oily  seeds),  with  which  bitter  and  astringent  qualities  are 
oflen  combined.  The  seeds  of  Bombax,  the  Silk-cotton  tree,  are  enveloped 
in  a  kind  of  cotton,  which  belongs  to  the  endocarp  and  not  to  the  seed;  and 
the  hairs,  being  perfectly  smooth  and  even,  cannot  be  spun.  Canoes  are  made 
from  the  trunk  of  Bombax,  in  the  West  Indies.  To  this  order  belongs  the 
famous  Baobab,  or  Monkey's-bread  of  Senegal  (Adansonia  digitata) ;  some 
trunks  of  which  are  from  sixty  to  eighty  feet  in  circumference  !  The  fruit  re- 
sembles a  gourd,  and  serves  for  vessels ;  it  contains  a  subacid  and  refrigerant, 
somewhat  astringent,  pulp;  the  mucilaginous  young  leaves  are  also  used  for 
food  in  time  of  scarcity;  the  dried  and  powdered  leaves  (Lalo)  are  ordinarily 
mixed  with  food,  and  the  bark  furnishes  a  coarse  thread,  which  is  made  into 
cordage  or  woven  into  cloth.  Cheirostemon  platanoides  ife  the  remarkable 
Hand-flower  tree  of  Mexico.  Two  plants  of  the  family  have  recently  been 
found  in  California,  by  Fremont. 


396 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


five  clusters,  distinct  or  somewhat  united,  one  of  each  parcel  often 
transformed  into  a  petaloid  scale  ;  anthers  two-celled.  Styles 
united  into  one.  Fruit  two  to  five-celled,  or,  by  obliteration,  one- 
celled  when  ripe.  In  other  respects  nearly  as  in  Malvaceae.  — 
Ex.  Tilia,  the  Linden,  or  Lime-tree  (Fig.  622),  represents  the  or- 
der in  northern  temperate  regions ;  the  other  genera  are  tropical. 
All  are  mucilaginous,  with  a  tough,  fibrous  inner  bark.  From  this 
dost  or  bass  of  the  Linden,  the  Russian  mats,  &c.,  are  made, 
whence  the  name  of  Bass  wood.  Gunny-bags  and  fishing-nets  are 
made  in  India  from  the  bark  of  Corchorus  capsularis ;  the  fibre  of 
which  is  called  Jute,  and  is  spun  and  woven.  The  light  wood  of 
the  Linden  is  excellent  for  wainscoting  and  carving :  its  charcoal 
is  used  for  the  manufacture  of  gunpowder.  It  is  said  that  a  little 
sugar  may  be  obtained  from  the  sap :  and  the  honey  made  from 
the  odorous  flowers  is  thought  to  be  the  finest  in  the  world.  The 
acid  berries  of  Grewia  sapida  are  employed  in  the  East  in  the 
majiufacture  of  sherbet.* 


*  Ord.  DIPTEROCARPEiE,  intermediate  in  some  respects  between 
TiliacesB  and  Ternstroemiacea3,  consists  of  a  few  tropical  Indian  trees,  with  a 
resinous  or  balsamic  juice.  Dryobalanops  aromatica,  a  large  tree  of  Sumatra 
and  Borneo,  yields  in  great  abundance  both  a  camphor  oil  and  solid  camphor: 


FIG.  622.  Flowering  branch  of  Tilia  Americana,  the  common  American  Linden  ;  the  flow- 
er slalk  cohering  with  the  bract.  623.  One  of  the  clusters  of  stamens  adhering  to  the  stami- 
nodium,  or  petaloid  scale.  624.  The  pistil.  62.5.  Cross-section  of  the  fruit,  which  has  become 
one-celled  by  the  obliteration  of  the  partitions,  and  one-seeded.  626.  Vertical  section  of  the 
seed,  magnified,  to  show  the  large  embryo  with  its  taper  radicle  and  foliaceous  crumpled  co- 
tyledons. (A  better  section  of  the  seed,  cut  in  the  direction  across  the  cotyledons,  is  shown  in 
Fig.  451.)    627.  Diagram  of  the  flower. 


THE  POLYPETALOUS  ORDERS.  397 

743.  Ord.  TernstrCBmiacefB  (the  Tea  Family).  Trees  or  shrubs, 
with  a  watery  juice,  alternate  simple  leaves  without  stipules,  and 
large  and  showy  flowers.  Calyx  of  three  to  seven  coriaceous  and 
concave  imbricated  sepals.  Petals  five  or  more,  imbricated  in 
aestivation.  Stamens  hypogynous,  indefinite,  monadelphous  or 
polyadelphous  at  the  base.  Capsule  several-celled,  usually  with  a 
central  column.  Seeds  few  in  each  cell,  large,  with  or  without 
albumen.  —  Ex.  Gordonia  (Loblolly  Bay),  Stuartia,  Thea  (Tea), 
Camellia.  Ornamental  plants,  natives  of  tropical  America,  except 
two  genera  in  the  Southern  United  States,  and  of  Eastern  Asia. 
The  leaves  of  Tea  contain  a  peculiar  extractive  matter,  and  a 
somewhat  stimulant  ethereal  oil. 

744.  Ord.  AurantiaceSB  {the  Orange  Family).  Trees  or  shrubs, 
with  alternate  leaves  (compound,  or  with  jointed  petioles),  destitute 
of  stipules,  dotted  with  pellucid  glands  full  of  volatile  oil.  Flowers 
fragrant.  Calyx  short,  urceolate  or  campanulate.  Petals  three  to 
five.  Stamens  inserted  in  a  single  row  upon  a  hypogynous  disk, 
often  somewhat  monadelphous  or  polyadelphous.  Style  cylindri- 
cal :  stigma  thickish.  Fruit  a  many-celled  berry,  with  a  leathery 
rind,  filled  with  pulp.  Seeds  without  albumen.  —  Ex.  Citrus,  the 
Orange  and  Lemon.  Nearly  all  natives  of  tropical  Asia ;  now  dis- 
persed throughout  the  warmer  regions  of  the  world,  and  cultivated 
for  their  beauty  and  fragrance,  and  for  their  grateful  fruit.  The 
acid  of  the  Lemon,  &c.,  is  the  citric  and  malic.  The  rind  abounds 
in  a  volatile  oil  (such  as  the  Oil  of  Bergamot  from  the  Lime),  and 
an  aromatic,  bitter  principle. 

745.  Ord.  MeliaceSB.  Trees  or  shrubs,  with  alternate,  usually 
compound  leaves,  destitute  of  stipules.  Calyx  of  three  to  five  se- 
pals. Petals  three  to  five.  Stamens  twice  as  many  as  the  petals, 
monadelphous,  inserted  with  the  petals  on  the  outside  of  a  hypogy- 
nous disk ;  the  anthers  included  in  the  tube  of  filaments.     Ovary 


both  are  found  deposited  in  cavities  of  the  trunk,  the  latter  frequently  in 
pieces  as  long  as  a  man's  arm,  weighing  ten  or  twelve  pounds.  It  is  more 
solid  than  common  camphor,  and  is  not  volatile  at  ordinary  temperatures.  It 
bears  a  high  price,  and  is  seldom  found  in  Europe  or  this  country,  but  is 
chiefly  carried  to  China  and  Japan.  A  thin  balsam,  called  wood-oil  in  India, 
and  used  for  painting  ships  and  houses,  is  yielded  by  some  species  of  Diptero- 
carpus  and  Shorea.  Shorea  robusta  yields  the  Dammer-pitch.  Vateria  Indica 
exudes  a  kind  of  copal,  the  G^im  Animi  of  commerce;  and  a  somewhat  aro- 
matic fatty  matter,  called  Piney  Talloic,  is  derived  from  the  seeds. 

34 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

several-celled,  with  one  or  two  ovules  in  each  cell :  styles  and 
stigmas  united  into  one.  Fruit  a  drupe,  berry,  or  capsule ;  the 
cells  one-seeded.  Seeds  without  albumen,  wingless.  —  Ex.  Melia 
Azedarach  (Pride  of  India),  naturalized,  as  an  ornamental  tree,  in 
the  Southern  States.  An  acrid  and  bitter  principle  pervades  this 
tropical  order. 

746.  Ord.  CedrelaceSB  (the  Mahogany  Family).  Trees  (tropical 
or  Australian),  with  hard  and  durable,  usually  fragrant  and  beauti- 
fully veined  wood ;  differing  botanically  from  Meliacese  chiefly  by 
their  capsular  fruit,  with  several  winged  seeds  in  each  cell.  —  Ex. 
The  Mahogany  (Swietenia  Mahagoni)  of  tropical  America,  reach- 
ing to  Southern  Florida.  The  Red-wood  of  Coromandel  is  the 
timber  of  Soymida  febrifuga  ;  the  Satin-wood^  of  Chloroxylon 
Swietenia  of  India ;  Yellow-wood,  of  the  Australian  Oxleya  xan- 
thoxyla,  dsc.  All  the  species  are  bitter,  astringent,  tonic,  often 
aromatic  and  febrifugal. 

747.  Ord.  LinaceSB  (the  Flax  Family).  Herbs,  with  entire  and 
sessile  leaves,  either  alternate,  opposite,  or  verticillate,  and  no 
stipules,  except  minute  glands  occasionally.  Flowers  regular  and 
symmetrical.  Calyx  of  three  or  five  persistent  sepals,  strongly 
imbricated.  Petals  as  many  as  the  sepals,  convolute  in  aestivation. 
Stamens  as  many  as  the  petals,  and  usually  with  as  many  inter- 
mediate teeth  representing  an  abortive  series,  all  united  at  the 
base  into  a  ring,  hypogynous.  Ovary  with  as  many  styles  and 
cells  as  there  are  sepals,  each  cell  with  two  suspended  ovules ;  the 
cells  in  the  capsule  each  more  or  less  perfectly  divided  into  two, 
by  a  false  partition  which  grows  from  the  back  (dorsal  suture) ; 
the  spurious  cells  one-seeded.  Embryo  straight :  cotyledons  flat, 
fleshy  and  oily,  surrounded  by  a  thin  albumen.  —  Ex.  Linum,  the 


Flax  (Fig.  628-631),  is  the  principal  representative  of  this  small 

FIG.  628.  Flower  of  Linum  perenne.  629.  Its  stamens  and  pistils.  630.  Cross-section  of 
its  capsule,  showing  the  incomplete  false  partition  from  the  back  of  each  cell.  63L  Section  of 
the  fruit  of  the  common  Flax,  where  the  false  partitions  completely  divide  each  proper  cell  into 
two. 


THE    POLYPETALOUS    ORDERS. 


399 


family.  The  tough  woody  fibre  of  the  bark  (flax)  is  of  the  high- 
est importance  :  the  seeds  yield  a  copious  mucilage,  and  the  fixed 
oil  expressed  from  them  is  applied  to  various  uses  in  the  arts.  The 
flowers  are  commonly  handsome.  The  flowers  of  the  succeeding 
families  are  formed  on  the  same  general  plan. 

748.  DM.  GeraniaceSB  {the  CraneshUl  Family).  Herbs  or  shrub- 
by plants,  commonly  strong-scented ;  with  palmately  veined  and 
usually  lobed  leaves,  mostly  with  stipules ;  the  lower  opposite. 
Flowers  regular,  or  somewhat  irregular.  —  Calyx  of  five  persistent 
sepals,  imbricated  in  aestivation.     Petals  five,  with  claws,  mostly 


convolute  in  aestivation.  Stamens  10,  the  five  exterior  hypogy- 
nous,  occasionally  sterile ;  the  filaments  all  broad  and  united  at 
the  base.  Ovary  of  five  two-ovuled  carpels, 
attached  to  the  base  of  an  elongated  axis  (gy- 
nohase)  to  which  the  styles  cohere :  in  fruit 
the  distinct  one-seeded  carpels  separate  from 
the  axis,  by  the  twisting  or  curling  back  of  the 
persistent  indurated  styles  from  the  base  up- 
wards. Seeds  with  no  albumen :  cotyledons 
convolute  and  plaited  together,  bent  on  the 
short  radicle.  —  Eo;.    Geranium  (Fig.  632-638),  or  Cranesbill. 

FIG.  632.  Radical  leaf  of  Geranium  maculatum  (Cranesbill).  633.  A  flowering  branch. 
634.  A  flower  with  the  calyx  and  corolla  removed,  showing  the  stamens,  &c.  635.  The  pistil 
.in  fruit ;  the  indurated  styles  separating  below  from  the  prolonged  axis,  and  curving  back  elas- 
ticalty,  carrying  with  them  the  membranous  carpels.  636.  A  magnified  seed.  637.  A  crosa- 
section  of  the  same,  showing  the  folded  and  convolute  cotyledons. 

FIG.  638.    Diagram  of  the  flower  of  a  Geranium. 


400  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Our  cultivated  Geraniums,  so  called,  from  the  Cape  of  Good  Hope, 
are  species  of  Pelargonium.  The  roots  are  simply  and  strongly 
astringent.  The  foliage  abounds  with  an  aromatic  resinous  matter 
and  an  ethereal  oil.  —  The  proper  symmetry  of  the  flower  is  ex- 
plained on  p,  267. 

749.  Orel.  Oxalulaceae  {the  Wood- Sorrel  Famihj).  Low  herbs, 
with  an  acid  juice,  and  alternate  compound  leaves ;  the  leaflets 
usually  obcordate.  Flowers  regular,  of  the  same  general  structure 
as  in  the  preceding  family,  except  the  gynajcium.  Carpels  five, 
united  into  a  compound  ovary,  with  the  styles  distinct ;  in  fruit 
forming  a  membranaceous  five-lobed  and  five-celled  capsule.  Seeds 
with  a  fleshy  outer  coat,  which  bursts  elastically  when  ripe,  with  a 
large  and  straight  embryo  in  thin  albumen.  —  Ex.  Oxalis,  the 
Wood-Sorrel.  The  herbage  is  sour,  as  the  name  denotes,  and 
contains  oxalic  acid.  The  foliage  is  remarkably  sensitive  in  some 
species.  The  tubers  of  some  South  American  species  (called  Ar- 
racacha),  filled  with  starch,  have  been  substituted  for  potatoes. 

750.  Ord.  Zygopliyllacese  differs  from  the  last  in  the  opposite, 
mostly  abruptly  pinnate  leaves,  distinct  stamens  (the  filaments  com- 
monly furnished  with  an  internal  scale.  Fig.  303),  and  the  styles 
united  into  one.  —  Ex.  Tribulus  and  Kallstroemia  (introduced  into 
the  Southern  States)  are  exalbuminous ;  the  latter  is  10-coccous, 
just  as  Linum  is,  by  a  false  partition.  Guaiacum  and  Larrea,  both 
in  Texas,  and  the  rest  of  the  family,  have  a  corneous  albumen. 
The  wood  of  Guaiacum  (Lignum-vitcB)  is  extremely  hard  and 
heavy,  and  yields  a  gum-resinous,  bitter,  and  acrid  principle  {Gum 
Guaiacum),  well  known  in  medicine. 

751.  Ord.  BalsaminaceSB  {the  Balsam  Family).  Annual  herbs, 
with  succulent  stems  filled  with  a  watery  juice.  Leaves  simple, 
without  stipules.  Flowers  irregular,  and  one  of  the  colored  sepals 
spurred  or  saccate.  Stamens  five,  cohering  by  an  internal  appen- 
dage. Compound  ovary  five-celled  :  stigmas  sessile.  Capsule 
bursting  elastically  by  five  valves.  Seeds  several,  without  albu- 
men, and  with  a  straight  embryo.  —  Ex.  Impatiens,  the  Balsam, 
or  Touch-me-not.  The  flowers  are  generally  showy.  Remark- 
able for  the  elastic  force  with  which  the  capsule  bursts  in  pieces, 
and  expels  the  seeds.  Somewhat  differently  irregular  blossoms 
are  presented  by  the 

752.  Ord.  Tropffiolaceffi  {the  Indian  Cress  or  Nasturtium  Family). 
Straggling  or  twining  herbs,  with  a  pungent  watery  juice,  and  pel- 


THE  POLYPETALOUS  ORDERS.  401 

tate  or  palmate  leaves.  Flowers  irregular.  Calyx  of  five  colored, 
united  sepals,  the  lower  one  spurred.  Petals  five  ;  the  two  upper 
arising  from  the  throat  of  the  calyx,  remote  from  the  three  lower, 
which  are  stalked.  Stamens  eight,  unequal,  distinct.  Ovary  three- 
lobed,  composed  of  three  united  carpels;  which  separate  from  the 
common  axis  when  ripe,  are  indehiscent,  and  one-seeded.  Seed 
filling  the  cell,  without  albumen  :  cotyledons  large,  thick,  and  con- 
solidated. —  Ex.  Tropaeolum,  the  Garden  Nasturtium,  from  South 
America,  where  there  are  a  few  other  species,  one  of  which  bears 
edible  tubers.  They  possess  the  same  acrid  principle  and  anti- 
scorbutic properties  as  the  Cruciferse.  The  unripe  fruit  of  Tropse- 
olum  majus  is  pickled,  and  used  as  a  substitute  for  capers. 

753.  Ord.  Limnanthaceae  differs  from  the  last  only  in  its  regular 
and  symmetrical  blossoms,  and  the  erect  instead  of  suspended 
seeds  ;  the  calyx  valvate  in  aestivation.  —  Ex.  Limnanthes  of  Cal- 
ifornia, and  Floerkea  of  the  Northern  United  States. 

754.  Ord.  Rutaceae  (the  Rue  Family).  Herbs,  shrubs,  or  trees  ; 
the  leaves  dotted  and  without  stipules.  Flowers  perfect.  Calyx 
of  four  or  five  sepals.  Petals  four  or  five.  Stamens  as  many  or 
two  to  three  times  as  many  as  the  petals,  inserted  on  the  outside  of 
a  hypogynous  disk.  Ovary  three-  to  five-lobed,  three-  to  five-celled, 
'yith  the  styles  united,  or  distinct  only  at  the  base,  during  ripening 
usually  separating  into  its  component  carpels,  which  are  dehiscent 
by  one  or  both  sutures.  Seeds  few,  mostly  with  albumen  ;  and  a 
Curved  embryo.  —  Ex.  Ruta  (the  Rue),  Dictamnus  (Fraxinella), 
of  Europe,  &c.,  and  Rutosma  of  Texas.  Diosma  and  its  allies,  of 
the  Cape  of  Good  Hope  and  New  Holland,  form  a  suborder,  or  a 
closely  allied  order.  Remarkable  for  their  strong  and  usually  un- 
pleasant odoF,  and  their 'bitterness  (as  in  the  common  Rue  of  the 
gardens),  owing  to  a  volatile  oil  and  a  resinous  matter ;  the  former 
is  so  abundantly  exhaled  by  the  Fraxinella  in  a  hot,  dry  day,  that  it 
is  vsaid  the  air  which  surrounds  it  may  be  set  on  fire.  Many  plants 
of  the  Diosma  tribe,  especially  those  of  Equinoctial  America,  con- 
tain a  bitter  alkaloid  principle,  and  possess  valuable  febrifugal 
properties.  The  most  important  is  the  Galipea,  which  furnishes 
the  Angostura  bark. 

755.  Ord.  Zanthoxylacese  (the  Prickly-Ash  Family).  Trees  or 
shrubs  ;  the  leaves  without  stipules,  and  punctate  with  pellucid  dots. 
Flowers  polygamous  or  dioecious.  Calyx  of  three  to  nine  sepals. 
Petals  as  many  as  the  sepals,  or  wanting.     Stamens  as  many  or 

34* 


402 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


twice  as  many  as  the  petals.  Carpels  two  or  more,  borne  on  the 
convex  or  elevated  receptacle,  either  united  or  separate  ;  in  the  lat- 
ter case  the  styles  usually  cohere  when  young.  Seeds  one  or  two 
in  each  cell  or  carpel,  with  a  smooth  and  shining  crustaceous  tes- 
ta, albuminous,  embryo  rather  large,  straight.  — Ex.  Zanthoxylum 
(Prickly  Ash)  is  the  type  of  this  order,  of  chiefly  American,  and 


nearly  all  tropical,  plants.    They  are  aromatic,  pungent,  stimulant, 
and  bitter ;  these  properties  chiefly  resident  in  the  bark. 

756.  Ord,  OchnaceSB  is  a  small  group,  nearly  allied  to  the  last, 
but  with  simple  dotless  leaves,  not  aromatic,  and  endowed  with 
purely  bitter  qualities  {Ex.  Castela,  in  Texas).  Some  plants  of  the 
family  have  a  scale  on  the  inner  side  of  each  filament,  as  in  Zygo- 
phyllacesB,  and  make  a  near  approach  to  Simarubaceae.* 


*  Ord.  SIMARUBACE^,  composed  of  a  few  tropical,  and  chiefly  Amer- 
ican, trees  and  shrubs,  is  of  some  importance  in  medicine.  The  wood 
abounds  in  an  excessively  bitter  extractive  principle,  called  Quassine.  The 
Q,uassia-wood  of  the  shops  is  derived  from  the  Q,uassia  amara  of  Surinam  and 

FIG.  639.  A  flowering  branch  of  Zanthoxylum  Americanum  (the  Northern  Prickly  Ash). 
640.  A  piece  of  a  leaf,  to  show  the  pellucid  dots.  641.  Staminate  flower.  642.  A  pistillate 
flower,  the  sepals  spread  open.  643.  Two  of  the  pistils ;  one  of  them  divided  vertically  to  show 
the  ovules.  644.  A  branch  in  fruit.  645.  One  of  the  dehiscent  pods,  and  the  seed.  646.  Ver- 
tical section  of  an  unripe  pod  and  seed  ;  the  latter  pendent  from  a  descending  funiculus,  show 
ing  a  slender  embryo  in  copious  albumen. 


THE  POLYPETALOUS  OEDERS.  403 

757.  Ord.  Anacardiaceae  (the  Cashew  Family).  Trees  or  shrubs, 
with  a  resinous  or  milky,  often  acrid  juice,  which  turns  blackish 
in  drying :  the  leaves  alternate,  without  stipules,  and  not  dotted. 
Flowers  small,  often  polygamous  or  dioecious.  Calyx  of  three  to 
five  sepals,  united  at  the  base.  Petals,  and  usually  the  stamens, 
as  many  as  the  sepals,  inserted  into  the  base  of  the  calyx  or  into  a 
hypogynous  disk.  Ovary  one-celled,  but  with  three  styles  or  stig- 
mas, and  a  single  ovule.  Fruit  a  berry  or  drupe.  Seed  without 
albumen.  Embryo  curved  or  bent.  —  Ex.  Rhus,  Anacardium 
(the  Cashew),  Pistacia.  Chiefly  tropical ;  but  several  species  of 
Rhus  are  indigenous  to  the  United  States.  The  acrid  resinous 
juice  is  used  in  varnishes ;  but  it  often  contains  a  caustic  poison. 
Even  the  exhalations  from  Rhus  Toxicodendron  (Poison  Oak,  Poi- 
son Ivy),  and  R.  venenata  (Poison  Sumach,  Poison  Elder),  as  is 
well  known,  severely  affect  many  persons,  producing  erysipelatous 
swellings,  &;c.  Their  juice  is  a  good  indelible  ink  for  marking 
linen.  But  the  common  Sumachs  (R.  typhina  and  R.  glabra)  are 
innocuous ;  their  astringent  bark  is  used  for  tanning ;  and  their 
sour  berries  (which  contain  bimalate  of  lime)  for  acidulated  drinks. 
The  oily  seeds  of  Pistacia  vera  (the  Pistacia-nut)  are  edible.  The 
drupe  of  Mangifera  Indica  (Mango)  is  one  of  the  most  grateful  of 
tropical  fruits.  The  kernel  of  the  Cashew-nut  (Anacardium  occi- 
dentale)  is  eatable ;  and  so  is  the  acid  enlarged  and  fleshy  pedun- 
cle on  which  the  nut  rests :  but  the  coats  of  the  latter  are  filled 
with  a  caustic  oil,  which  blisters  the  skin ;  while  from  the  bark  of 
the  tree  a  bland  gum  exudes.* 

Guiana,  or  more  commonly,  at  least  of  late  years,  from  Picraena  excelsa  of 
Jamaica.     It  has  been  used  as  a  substitute  for  hops  in  the  manufacture  of  beer. 

*  Ord.  BURSERACEyE,  including  a  great  part  of  what  were  formerly 
called  Terebinthacea3,  consists  of  tropical  trees,  with  a  copious  resinous  juice, 
compound  leaves  usually  marked  with  pellucid  dots,  and  small,  commonly 
perfect  flowers ;  with  valvate  petals,  a  two-  to  five-celled  ovary,  and  drupa- 
ceous fruit.  Their  balsamic  juice,  which  flows  copiously  when  the  trunk  is 
wounded,  usually  hardens  into  a  resin.  The  Olibannm,  used  as  a  fragrant  in- 
cense, the  Balm  of  Gilead,  or  Balsam  of  Mecca,  Myrrh,  and  the  Bdellium,  are 
derived  from  Arabian  species  of  the  order;  the  East  Indian  Gum  Elemi,  from 
Canarium  commune;  Balsam,  of  Acouchi,  wad.  similar  substances,  from  vari- 
ous American  trees  of  this  family. 

Ord.  AMYRIDACEiE  consists  of  a  few  West  Indian  plants,  intermediate 
as  it  were  between  Burseracess  and  Leguminosae,  and  distinguished  from  the 
former  chiefly  by  their  simple  and  solitary  ovary.  One  species  of  Amyris 
grows  in  Florida.  Their  properties  are  the  same  as  the  preceding;  the  trunks 
abounding  in  a  fragrant  resinous  juice. 


404 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


758.  Ord.  Malpighiaceae  is  a  large  tropical  family  (with  one  or 
two  representatives  in  Texas),  which  differs  from  Aceracese  in  its 
more  symmetrical  flowers,  trimerous  gynsecium,  solitary  ovules, 
the  want  of  a  disk,  and  in  the  entire  leaves,  &c. 

759.  Ord.  AceraceSB  {the  Maple  Family).  Trees  or  shrubs,  with 
opposite  leaves  and  no  stipules.  Flowers  small,  polygamous,  reg- 
ular, sometimes-  perfect,  in  racemes,  corymbs,  or  fascicles,  often 
preceding  the  leaves.  Calyx  mostly  of  five  sepals,  more  or  less 
united.  Petals  as  many  as  the  sepals,  or  none.  Stamens  three  to 
twelve,  seldom  agreeing  in  number  with  the  sepals,  inserted  on  or 
around  a  hypogynous  disk.  Ovary  of  two  more  or  less  united 
carpels ;  each  carpel  forming  a  samara  in  fruit.  Ovules  two  in 
each  cell.  Seeds  solitary,  destitute  of  albumen.  Embryo  coiled. 
—  Ex.  Acer,  the  Maple  ;  useful  timber-trees  of  northern  temper- 


ate regions.     Sugar  is  yielded  by  the  vernal  sap  of  Acer  saccha- 
rinum,  and  in  less  quantity  by  A.  dasycarpum  and  other  species. 


FIG,  647.  A  branch  of  Acer  dasycarpum  (the  White  Soft  Maple)  with  staminate  flowers. 
648.  A  separate,  enlarged  staminate  flower.  649.  Branch  with  pistillate  flowers.  650.  A  sepa- 
rate fertile  flower;  the  bracts,  &c.,  of  the  cluster  cut  away.  651.  The  same  enlarged,  with  the 
calyx  cut  away.  652.  A  cluster  showing  the  fruiting  ovaries  expanding  into  wings  (reduced  in 
size).    65.3.  Ripe  fruit;  one  of  the  samaras  cut  open  to  show  the  seed.    654.  A  leaf. 


THE    POLYPETALOUS    ORDERS. 


405 


760.  Ord.  Sapindacea;  {the  Soapberry  Family).  Trees,  shrubs, 
or  climbers,  with  tendrils,  rarely  herbs  (nearly  all  tropical  and 
American) ;  with  alternate  and  mostly  compound  leaves.  Flowers 
small,  unsymmetrical,  usually  irregular  and  polygamous.  Calyx 
of  four  or  five  sepals.  Petals  irregular  and  often  one  fewer  than 
the  sepals,  sometimes  wanting.  Stamens  eight  to  ten.  Ovary  two- 
or  three-celled  ;  the  styles  or  stigmas  more  or  less  united.  Seeds 
usually  with  an  aril,  destitute  of  albumen.  Embryo  coiled  ;  the 
cotyledons  usually  thick  and  fleshy.  —  Ex.  Sapindus  (Soapberry, 
one  species  of  which  is  indigenous  to  the  southern  borders  of  the 
United  States) ;  and  Cardiospermum,  which  is  a  climbing  herb, 
with  a  bladdery  capsule,  often  met  whh  in  gardens.  They  are  as- 
tringent and  bitter.  The  fruit  of  Sapindus  is  used  for  soap.  The 
leaves  of  true  Sapindacese  are  alternate.  Inseparably  connected 
with  this  order  is  the 

761.  Subord.  HippocastanaceiB.     Trees  or  shrubs;    with  opposite 


digitate  leaves,  without  stipules.     Fruit  roundish,  coriaceous,  de- 


FIG.  655.  Flowering  branch  of  iEsculus  Pavia,  a  species  of  Buckeye.  656.  A  flower. 
657.  Flower  with  the  calyx  and  two  of  the  petals  removed.  658.  A  ground-plan  of  the  flower, 
showing  that  its  parts  are  unsymmetrical.  659.  Vertical  section  of  an  ovary,  showing  two  of 
the  cells  with  a  pair  of  ovules  in  each,  one  ascending,  one  descending.  660.  Cross-section  of 
an  ovary.  661.  Cross-section  of  the  immature  fruit;  only  one  fertile  seed;  the  others  abortive, 
662.  The  dehiscent  fruit. 


406  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

hiscent,  with  one  to  three  very  large  seeds,  resembling  chestnuts. 
Embryo  very  large  and  fleshy,  showing  a  two-leaved  plumule  : 
the  cotyledons  united.  —  Ex.  iEsculus,  the  Horsechestnut,  and 
Buckeye :  fine  ornamental  trees.  The  large,  starchy  seeds  are 
nutritious,  but  they  contain  a  bitter  principle  which  is  more  or  less 
noxious.  Those  of  M.  Pavia  are  used  to  stupefy  fish.  The  root 
of  the  same  species,  according  to  Elliott,  is  employed  as  a  substi- 
tute for  soap. 

762.  Ord.  CelastraceJC  (the  Spindle-tree  Family).  Shrubs  or  trees, 
with  alternate  or  opposite  simple  leaves.  Calyx  of  four  or  five 
sepals,  imbricated  in  aestivation.  Petals  as  many  as  the  sepals, 
inserted  under  the  flat  expanded  disk  which  closely  surrounds  the 
ovary,  imbricaled  in  aestivation.  Stamens  as  many  as  the  petals, 
and  alternate  with  them,  inserted  on  the  margin  or  upper  surface 
of  the  disk.  Ovary  free  from  the  calyx.  Fruit  a  capsule  or  berry, 
with  one  or  few  seeds  in  each  cell.  Seeds  usually  arilled,  albu- 
minous, with  a  large  and  straight  embryo.  —  Ex.  Celastrus  (False 
Bittersweet),  Euonymus  (Burning  Bush,  Spindle-tree) :  they  are 
all  somewhat  bitter  and  acrid  ;  but  of  little  economical  importance. 
The  crimson  capsules  and  bright  scarlet  arils  of  Euonymus  atro- 
purpureus  and  E.  Americanus  (sometimes  called  Strawberry-tree), 
present  a  striking  appearance  when  the  fruit  is  ripe. 

763.  Ord.  RhamnaceaB  (the  Buckthorn  Family).  Shrubs  or  trees, 
often  with  spinose  branches ;  the  leaves  mostly  alternate,  simple. 
Flowers  small.  Calyx  of  four  or  five  sepals,  united  at  the  base, 
valvate  in  aestivation.  Petals  four  or  five,  cucullate  or  convolute, 
inserted  on  the  throat  of  the  calyx,  sometimes  wanting.  Stamens 
as  many  as  the  petals,  inserted  with  and  opposite  them  !  Ovary 
sometimes  coherent  with  the  tube  of  the  calyx,  and  more  or  less 
immersed  in  a  fleshy  disk,  with  a  single  erect  ovule  in  each  cell. 
Fruit  a  capsule,  berry,  or  drupe.  Seeds  not  arilled.  Embryo 
straight,  large,  in  sparing  albumen.  —  Ex.  Rhamnus  (Buckthorn) 
is  the  type  of  the  order.  Ceanothus  is  peculiar  to  North  America  ; 
just  as  some  genera  are  to  the  Cape,  and  others  to  New  Holland. 
The  berries  of  most  species  of  Rhamnus  are  somewhat  nauseous  ; 
but  those  of  Zizyphus  are  edible.  The  genuine  Jujube  paste  is 
prepared  from  those  of  Z.  Jujuba  and  Z.  vulgaris  of  Asia.  Syrup 
of  Buckthorn  and  the  pigment  called  Sap-green  are  prepared  from 
the  fruit  of  Rhamnus  catharticus.  The  herbage  and  bark  in  this 
order  are  more  or  less  astringent  and  bitter.     An  infusion  of  the 


THE  POLYPETALOUS  ORDERS. 


407 


leaves  of  Ceanothus  Americanus  (thence  called  New  Jersey  Tea) 
has  been  used  as  a  substitute  for  tea. 

764.  Ord.  StaphyleaceSB  {the  Bladder-nut  Family)^  consisting  chief- 
ly of  Staphylea,  is  intermediate  between  the  order  Sapindacese, 
from  which  it  differs  in  its  more  symmetrical  flowers  and  straight 
embryo  in  fleshy  albumen,  and  the  order  Celastracese,  from  which 
the  compound  leaves,  partly  separate  pistils,  and  bony  seeds  distin- 
guish it. 

765.  Ord.  YitaceSB  {the  Vine  Family).  Shrubby  plants  climbing 
by  tendrils,  with  simple  or  compound  leaves,  the  upper  alternate. 
Flowers  small,  often  polygamous  or  dioecious.     Calyx  very  small. 


entire  or  four-  or  five-toothed,  lined  with  a  disk.     Petals  four  or 


FIG.  663.  A  branch  of  the  Grape  ;  showing  the  nature  of  the  tendrils.  664.  A  flower;  the 
petals  separating  from  the  base,  and  falling  off  together  without  expanding.  665.  A  flower 
from  which  the  petals  have  fallen;  the  lobes  of  the  disk  seen  alternate  with  the  stamens. 
666.  Vertical  section  through  the  ovary  and  the  base  of  the  flower:  a,  calyx,  the  limb  of  which 
is  a  mere  rim:  6,  petal;  having  the  stamen,  c,  directly  before  it;  and  the  lobes  of  the  disk 
are  shown  between  this  and  the  ovary.  667.  A  seed.  668.  Section  of  the  seed ;  showing  the 
thick  crustaceous  testa,  and  the  albumen,  at  the  base  of  which  is  the  minute  embryo.  669.  A 
horizontal  plan  of  the  flower. 


408 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


five,  inserted  upon  the  outside  of  the  disk,  valvate  in  aestivation, 
sometimes  cohering  by  their  tips,  and  caducous.  Stamens  as 
many  as  the  petals,  and  opposite  them  !  Ovary  two-celled,  with 
two  erect  ovules  in  each  cell.  Fruit  a  berry.  Seeds  with  a  bony 
testa,  and  a  small  embryo  in  hard  albumen.  —  Ex.  Vitis  (the 
Vine),  Ampelopsis  (the  Virginia  Creeper).  The  fruit  of  the  Vine 
is  the  only  important  product  of  the  order.  The  acid  of  the  grape, 
which  also  pervades  the  young  shoots  and  leaves,  is  chiefly  the 
tartaric.  Grape-sugar  is  very  distinct  from  cane-sugar,  and  the 
only  kind  that  can  long  exist  in  connection  with  acids.  —  The  sym- 
metry of  the  flower  is  spoken  of  on  p.  269. 

766.  Ord.  PolygalaceSB  (the  Milkioort  Family),  Herbs  or  shrubby 
plants,  with  simple  entire  leaves,  destitute  of  stipules  ;  ihe  roots 
sometimes  with  a  milky  juice.  Pedicels  with  three  bracts.  Flow- 
ers perfect,  unsymmetrical,  and  irregular,  falsely  papilionaceous. 
Calyx  of  five  irregular  sepals ;  the  odd  one  superior,  the  two  inner 
{wings)  larger,  and  usually  petaloid.    Petals  usually  three,  inserted 


672 


670  673 


on  the  receptacle,  more  or  less  united  ;  the  anterior  {keel)  larger 


FIG,  670.  Polygalapaucifolia.  671.  A  flower,  enlarged.  672.  The  calyx  displayed.  673.  The 
corolla  and  stamineal  lube  laid  open.  674.  The  pistil  and  the  free  portion  of  the  stamens. 
675.  Vertical  section  of  the  ovary.  676.  Vertical  section  of  the  seed,  showing  the  large  em- 
bryo and  scanty  albumen. 


THE  POLYPETALOUS  ORDERS.  409 

than  the  rest.  Stamens  six  to  eight,  combined  in  a  tube,  which  is 
split  on  the  upper  side,  and  united  below  with  the  claws  of  the  pet- 
als :  anthers  innate,  mostly  one-celled,  opening  by  a  pore  at  the 
apex.  Ovary  compound,  two-celled,  with  a  single  suspended 
ovule  in  each  cell :  style  curved  and  often  hooded.  Capsule  flat- 
tened. Seeds  usually  with  a  caruncle.  Embryo  straight,  large, 
in  fleshy,  thin  albumen.  —  Ex.  Polygala,  the  type  of  the  order,  is 
dispersed  nearly  throughout  the  world.  A  bitter  principle  per- 
vades the  order  ;  and  many  species  also  yield  a  peculiar  acrid  ex- 
tractive matter.  The  Polygala  Senega  (Seneca  Snakeroot)  is  the 
most  important  medicinal  plant  of  the  family.  Many  other  species 
are  employed  medicinally  in  Brazil,  Peru,  Nepaul,  &c.  ;  where, 
like  our  own,  they  are  reputed  antidotes  to  the  bites  of  venomous 
reptiles. 

767.  Ord.  Krameriacea;  (the  Rhatany  Family)  consists  of  the  genus 
Krameria  only,  which  has  ordinarily  been  annexed  to  the  Polyga- 
lacesB ;  but  it  is  much  nearer  the  Leguminosse,  having  the  odd 
sepal  inferior,  a  simple  unilocular  pistil,  and  an  exalbuminous 
seed.  In  fact,  it  is  only  distinguishable  from  the  latter  by  the  hy- 
pogynous  stamens  and  the  want  of  stipules.  The  roots  contain  a 
red  coloring  matter,  and  are  astringent  without  bitterness.  Rhat- 
any-root,  used  to  adulterate  port- wine,  and  as  an  ingredient  in 
tooth-powders,  &c.,  is  the  produce  of  Krameria  triandra  of  Pferu. 
That  of  our  own  Southern  K.  lanceolata  possesses  the  same  prop- 
erties. 

768.  Ord.  Leguminosse  {the  Pulse  Family).  Herbs,  shrubs,  or 
trees,  with  alternate  and  usually  compound  leaves,  furnished  with 
stipules.  Calyx  mostly  of  five  sepals,  more  or  less  united ;  the 
odd  sepal  inferior  (Fig.  382).  Corolla  of  five  petals,  either  papil- 
ionaceous or  regular.  Stamens  perigynous,  or  sometimes  hypogy- 
nous.  Ovary  single  and  simple.  Fruit  a  legume,  various  forms 
of  which  are  shown  in  Fig.  438-446.  Seeds  destitute  of  albu- 
men. —  This  immense  family  is  divided  into  three  principal  sub- 
orders ;  namely  : 

769.  Subord.  Papilionacca;  {the  Proper  Pulse  Family) ;  which  has 
the  papilionaceous  flower,  already  illustrated  (468,  Fig.  317-321), 
ten  stamens  (or  rarely  fewer),  which  are  diadelphous  (Fig.  308), 
sometimes  monadelphous  (Fig.  307,324),  or  rarely  distinct  (Fig. 
^22),  inserted  into  the  base  of  the  calyx.  Radicle  bent  on  the 
large  cotyledons.     Ticaves  only  once  compound,  the  leaflets  entire. 

35 


410  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

{Ex.,  the  Pea,  Bean,  Locust,  Clover,  &c.)  The  vexillum  is  the 
largest  petal,  and  external  in  aestivation,  in  all  true  papilionaceous 
corollas,  as  in  the  diagram.  Fig.  382.     But  in  the 

770.  Subord.  CaesalpineEB  (to  which  Cassia,  Cercis,  and  the  Honey- 
Locust  belong),  the  corolla  gradually  loses  its  papilionaceous  char- 
acter, and  always  has  the  vexillum,  or  superior  petal,  covered  by 
the  lateral  ones  in  aestivation  ;  the  stamens  are  distinct,  and  the 
embryo  straight.     The  leaves  are  often  bipinnate. 

771.  Subord.  MimosSB  (a  large  group  to  which  the  Acacia  and  the 
Sensitive  Plant  belong)  has  a  perfectly  regular  calyx  and  corolla, 
the  latter  mostly  valvate  in  sestivation  and  hypogynous,  as  well  as 
the  stamens,  which  are  sometimes  definite,  but  often  very  numer- 
ous ;  and  the  embryo  is  straight.  The  leaves  are  frequently  iri- 
pinnale. 

772.  Papilionacese  are  found  in  every  part  of  the  world,  from 
the  tropics  to  the  frigid  zones  :  Csesalpineoe  and  Mimosese  are  con- 
fined to  the  tropical  and  warmer  temperate  regions.  —  A  full  ac- 
count of  the  useful  plants  and  products  of  this  large  order  would 
require  a  separate  volume.  Many,  such  as  Clover,  Lucerne  (Med- 
icago  sativa),  &c.,  are  extensively  cultivated  for  fodder ;  Peas  and 
Beans,  for  pulse.  The  roots  of  the  Licorice  (Glycirrhiza  glabra  of 
Southern  Europe)  abound  in  a  sweet  mucilaginous  juice,  from 
which  the  pectoral  extract  of  this  name  is  prepared.  The  sweet 
pulp  of  the  pods  of  Ceratonia  Siliqua  (Carob-tree  of  the  South  of 
Europe,  &c.),  of  the  Honey-Locust  (Gleditschia),  &c.,  is  likewise 
eaten.  The  laxative  pulp  of  Cathartocarpus  Fistula,  and  of  the 
Tamarind,  is  well  known ;  the  latter  is  acidulated  with  malic,  and 
a  little  tartaric  and  citric  acid.  —  A  peculiar  volatile  principle 
(called  Coumarin)  gives  its  vanilla-like  fragrance  to  the  well-known 
Tonka-bean,  and  to  the  Melilotus,  or  Sweet  Clover.  The  flowers 
and  seeds  of  the  latter  and  of  Trigonella  cserulea  give  the  peculiar 
odor  to  Scheipzeiger  cheese.  —  Astringents  and  tonics  are  also 
yielded  by  this  order :  such  as  the  African  Pterocarpus  erinaceus, 
the  hardened  red  juice  of  which  is  Gum  Kino  ;  that  of  P.  Draco,  of 
Carthagena,  &c.,  is  Dragon* s  Blood.  The  bark  of  most  Acacias 
and  Mimosas  contains  a  very  large  quantity  of  tannin,  and  is  like- 
ly to  prove  of  great  importance  in  tanning.  The  valuable  astrin- 
gent called  Catechu  is  obtained  by  boiling  and  evaporating  the 
heart-wood  of  the  Indian  Acacia  Catechu.  —  Leguminosse  yield 
the  inost  important  coloring  matters ;  such  as  the  Brazil-wood,  the 


THE  POLYPETALOUS  ORDERS.  411 

Logwood  of  Campeachy  (the  peculiar  coloring  principle  of  which 
is  called  Hcpmatin)^  and  the  Red  Sandal-wood  of  Ceylon.  Most 
important  of  all  is  Indigo^  which  is  prepared  from  the  fermented 
juice  of  the  Indigofera  tinctoria  (a  native  of  India),  and  also  from 
I.  cserulea,  and  other  species  of  the  genus.  This  substance  is 
highly  azotized,  and  is  a  violent  poison.  —  Te  the  same  order  we 
are  indebted  for  valuable  resins  and  balsams ;  such  as  the  Mexican 
Copal^  Balsam  of  Copaiva  of  the  West  Indies,  Para,  and  Brazil, 
the  bitter  and  fragrant  Balsam  of  Peru,  and  the  sweet,  fragrant, 
and  stimulant  Balsam  of  Tolu.  —  It  also  furnishes  the  most  useful 
gums ;  of  which  we  need  only  mention  Gum  Tragacanth,  derived 
from  Astragalus  verus  of  Persia,  &;c.  ;  and  Gum  Arabic,  the  prod- 
uce of  numerous  African  species  of  Acacia.  The  best  is  said  to 
be  obtained  from  Acacia  vera,  which  extends  from  Senegal  to 
Egypt ;  while  Gum  Senegal  is  yielded  by  A.  Verek,  and  some  other 
species  of  the  River  Gambia.  The  Senna  of  commerce  consists  of 
the  leaves  of  several  species  of  Cassia,  of  Egypt  and  Arabia.  C. 
Marilandica  of  this  country  is  a  succedaneum  for  the  officinal  ar- 
ticle. —  More  acrid,  or  even  poisonous  properties,  are  often  met 
with  in  the  order.  The  roots  of  Baptisia  tinctoria  (called  Wild  In- 
digo, because  it  is  said  to  yield  a  little  of  that  substance),  of  the 
Broom,  and  of  the  Dyers'  Weed  (Genista  tinctoria,  used  for  dying 
yellow),  possess  such  qualities  ;  while  the  seeds  of  Laburnum,  &c., 
are  even  narcotico-acrid  poisons.  The  branches  and  leaves  of 
Tephrosia,  and  the  bark  of  the  root  of  Piscidia  Erythrina  (Jamaica 
Dogwood,  which  is  also  found  in  Southern  Florida),  are  commonly 
used  in  the  West  Indies  for  stupefying  fish.  Cowitch  is  the  sting- 
ing hairs  of  the  pods  of  Mucuna  pruriens  of  the  West,  and  M.  pru- 
rita  of  the  East,  Indies.  —  Among  the  numerous  valuable  timber- 
trees,  our  own  Locust  (Robinia  Pseudacacia)  must  be  mentioned  ; 
and  also  the  Rose-wood  of  commerce,  the  produce  of  a  Brazilian 
species  of  Mimosa.  Few  orders  furnish  so  many  plants  cultivated 
for  ornament. 

773.  Ord.  Rosacea;  (the  Bose  Family).  Trees,  shrubs,  or  herbs, 
with  alternate  leaves,  usually  furnished  with  stipules.  Flowers 
regular.  —  Calyx  of  five  (rarely  three  or  four)  more  or  less  united 
sepals,  and  often  with  as  many  bracts.  Petals  as  many  as  the  se- 
pals (rarely  none),  mostly  imbricated  in  aestivation,  inserted  on  the 
edge  of  a  thin  disk  that  lines  the  tube  of  the  calyx.  Stamens  peri- 
gynous,  indefinite,  or  sometimes  few,  distinct.     Ovaries  with  soli- 


412 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


tary  or  few  ovules :  styles  often  lateral.  Albumen  none.  Em- 
bryo straight,  with  broad  and  flat  or  plano-convex  cotyledons  (Fig. 
457).  —  This  important  order  is  divided  into  four  suborders ; 
namely  : 

774.  Subord.  ChrysobalaneOB  (the  Cocoa-plum  Family).  Ovary 
solitary,  free  from  the  calyx,  or  else  cohering  with  it  at  the  base 
on  one  side  only,  containing  two  erect  ovules :  style  arising  from 
the  apparent  base.  Fruit  a  drupe.  Trees  or  shrubs.  —  Ex.  Chry- 
sobalanus. 

775.  Subord.  AmygdaleSB  (the  Almond  or  Plum  Family).  Ovary 
solitary,  free  from  the  deciduous  calyx,  with  two  suspended  ovules, 
and  a  terminal  style.  Fruit  a  drupe  (Fig.  447,  448).  Trees  or 
shrubs.  —  Ex.  Amygdalus  (the  Almond,  Peach,  &c.),  Prunus  (the 
Plum),  Cerasus  (the  Cherry). 

776.  Subord.  Rosaces  proper.     Ovaries  several,  numerous,  or  rare- 


FIG.  677.  The  Strawberry  (Fragaria).  678,  Half  of  a  flower,  divided  vertically,  from  which 
the  petals  are  removed;  showing  the  perigynous  insertion  of  the  stamens,  and  the  enlarged 
receptacle,  which,  increasing  in  size,  forms  the  pulpy,  edible  fruit,  bearing  the  achenia,  or  real 
fruits,  on  its  surface.  679.  One  of  the  carpels  magnified,  showing  the  lateral  style.  630.  Fruit 
of  the  Blackberry  (Rubus  villosus),  with  a  longitudinal  section:  here  the  elongated  receptacle 
does  not  enlarge,  but  the  ovaries  become  drupes.  631.  Section  of  the  endocarp;  the  cavity  of 
which  is  filled  by  the  seed,  and  that  by  the  embryo,  with  its  large  cotyledons.  632.  A  flower 
of  Sanguisorba  Canadensis,  enlarged.  683.  Vertical  section  of  the  same  in  fruit;  the  solitary 
ovary  inclosed  by,  but  not  coherent  with,  the  persistent  calyx-tube  ;  the  single  seed  with  its 
large  embryo  filling  the  achenium. 


THE    POLYPETALOUS    ORDERS. 


413 


ly  solitary,  free  from  the  calyx  (which  is  often  bracteolate,  as  if 
double),  but  sometimes  inclosed  in  its  persistent  tube,  in  fruit  be- 
coming either  follicles  or  achenia.  Styles  terminal  or  lateral. 
Herbs  or  shrubs.  —  The  three  tribes  of  this  suborder  are  Tribe  1. 
Spireje,  where  the  fruit  is  a  follicle.  Ex.  Spiraea  and  Gillenia. 
Tribe  2.  Dryade^,  where  the  fruits  are  achenia,  or  sometimes 
little  drupes,  and  when  numerous  crowded  on  a  conical  or  hem- 
ispherical torus.  Ex.  Dryas,  Agrimonia,  Potentilla,  Fragaria 
(Strawberry),  Rubus  (Raspberry  and  Blackberry).  Tribe  3.  Ro- 
SE.E,  where  numerous  achenia  cover  the  hollow  torus  which  lines 
the  urn-shaped  calyx-tube  ;  and  the  latter,  being  contracted  at  the 
mouth,  and  becoming  fleshy  or  berry-like,  forms  a  kind  of  false 
pericarp  ;  as  in  the  Rose. 

777.  Subord.  Pomes  {the  Pear  Family).  Ovaries  two  to  five,  or 
rarely  solitary,  cohering  with  each  other  and  with  the  thickened 
and  fleshy  or  pulpy  calyx-tube  ;  each  with  one  or  few  ascending 
seeds.  Trees  or  shrubs.  —  Ex.  Crataegus  (the  Thorn),  Cydonia 
(the  Quince),  Pyrus  (the  Apple,  Pear,  &c.). 

778.  This  important  order  is  diffused  through  almost  every  part 


of  the  world ;  but  chiefly  abounds  in  temperate  climates,  where  it 


FIG.  684.  Vertical  section  of  an  unexpanded  Rose,  showing  the  attachment  of  the  carpels  to 
the  lining  of  the  calyx-tube,  and  of  the  stamens  and  petals  to  its  summit  or  edge.  68.5.  Vertical 
section  of  the  fruit  of  the  Quince,  exhibiting  the  carpels  invested  by  the  thickened  calyx  which 
forms  the  edible  part  of  the  fruit ;  one  of  the  ovaries  laid  open  to  show  the  seeds.  686.  A  mag- 
nified seed ;  the  raphe  and  chalaza  conspicuous.  6S7.  The  embryo.  688.  Cross-section  of  an 
apple.    639.  Flower,  &;c.,  of  the  American  Crab- Apple  (Pyrus  coronaria). 

35* 


414  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

furnishes  the  most  important  fruits.  It  is  destitute  of  unwholesome 
qualities,  with  one  or  two  exceptions  ;  namely,  1st.  The  bark, 
leaves,  and  kernel  of  Amygdalese  contain  prussic  acid,  as  is  indicat- 
ed by  their  peculiar  odor,  —  a  trace  of  which  is  perceived  in  some 
species  of  Spirsea,  and  in  the  Mountain  Ash,  &c.,  among  Pomese  ; 
and  2d.  The  root  of  Gillenia  (Bowman's  Root,  Indian  Physic)  is 
emetic  in  large  doses,  but  in  small  doses  it  acts  as  a  tonic.  The 
bark  and  root  in  all  are  astringent.  The  bark  of  Amygdalese  also 
exudes  gum.  That  of  the  Wild  Black  Cherry  is  febrifugal ;  and  the 
timber  is  useful  in  cabinet-work.  The  leaves  of  Cerasus  Carolini- 
ana  contain  so  much  prussic  acid  as  to  destroy  cattle  that  feed  upon 
them.  It  takes  the  place  in  this  country  of  the  Cerasus  Lauro-ce- 
rasus  (Cherry -Laurel)  of  the  Old  World,  from  which  the  poisonous 
Laurel-water  and  the  virulent  Oil  of  Laurel  are  obtained.  Sweet 
and  bitter  almonds  are  the  seeds  of  varieties  of  Amygdalas  com- 
munis (indigenous  to  the  East),  differing  in  the  quantity  of  the 
prussic  acid  they  contain  :  the  oil  of  the  former  resembles  olive-oil ; 
that  of  the  latter  is  a  deadly  poison.  Of  the  Peach,  Apricot,  Nec- 
tarine, Plum,  and  Cherry,  it  is  unnecessary  to  speak.  The  kernels, 
as  well  as  the  flowers,  of  the  former,  especially,  abound  in  prussic 
acid.  —  The  strawberry,  raspberry,  and  blackberry  are  the  princi- 
pal fruits  of  the  proper  Rosacese.  The  leaves  of  Rosa  centifolia 
are  more  commonly  distilled  for  Rose-water :  and  Attar  of  Roses 
is  obtained  from  R.  Damascena,  &c.  —  Pomaceous  fruits,  such  as 
the  apple,  pear,  quince,  services,  medlar,  &c.,  yield  to  none  in  im- 
portance :  their  acid  is  usually  the  malic. 

779.  Ord.  CalycanthaceSB.  Shrubs,  with  quadrangular  stems 
(which  when  old  exhibit  four  axes  of  growth  exterior  to  the  old 
wood),  opposite  entire  leaves  without  stipules,  and  solitary,  axillary 
and  terminal,  lurid  flowers.  Calyx  of  numerous  somewhat  thick- 
ened colored  sepals,  in  several  rows,  confounded  with  the  petals, 
all  united  below  into  a  fleshy  tube  or  cup,  bearing  numerous  sta- 
mens upon  its  rim.  Outer  stamens  with  adnate  extrorse  anthers : 
the  inner  sterile.  Ovaries  indefinite,  two-ovuled,  becoming  hard 
achenia  in  fruit,  inserted  on  the  whole  inner  surface  of  the  disk 
which  lines  the  calyx-tube,  in  which  they  are  inclosed,  as  in  the 
Rose.  Albumen  none.  Cotyledons  convolute.  —  Consists  of  two 
genera ;  namely,  Calycanthus  (Carolina  Allspice,  Sweet-scent- 
ed Shrub,  &c.),  and  Chimonanthus,  of  Japan.  They  are  cul- 
tivated for  their  fragrant  flowers.     The  bark  and  foliage  of  Caly- 


THE    POLYPETALOUS    ORDERS. 


415 


canthus  exhales  a  camphoric  odor ;    and  the  flowers  a  fragrance 
not  unlike  that  of  strawberries. 


780.  Ord.  MyrtaceSB  {the  Myrtle  Family),  Trees  or  shrubs,  with 
opposite  and  simple  entire  leaves,  which  are  punctate  with  pellucid 
dots,  and  usually  furnished  with  a  vein  running  parallel  with  and 
close  to  the  margin  ;  without  stipules.  Calyx-tube  adherent  to  the 
compound  ovary  ;  the  limb  four-  or  five-cleft,  valvate  in  aestivation. 
Petals  four  or  five,  or  sometimes  wanting.  Stamens  indefinite, 
usually  with  long  filaments  and  small  round  (introrse)  anthers. 
Style  one.  Seeds  usually  numerous,  destitute  of  albumen.  — 
Ex.  Myrtus,  the  Myrtle,  is  the  most  familiar  representative  of  this 
beautiful  tropical  and  subtropical  order ;  which  is  well  distinguished 
from  its  allies  by  its  opposite  dotted  leaves  and  aromatic  proper- 
ties. The  species  abound  in  a  pungent  and  aromatic  volatile  oil, 
and  an  astringent  principle.  Cloves  are  the  dried  flower-buds  of 
Caryophyllus  aromaticus.  Pimento  (Allspice)  is  the  dried  fruit  of 
Eugenia  Pimenta.     Cajeput  oil,  a  powerful  sudorific,  is  distilled 


FIG.  690.  Flowers  of  Caly canthus  floridus.  691.  Vertical  section  of  a  flower,  showing  the 
hollow  receptacle,  &c. ;  the  floral  envelopes  cut  away,  692.  A  stamen,  seen  from  without. 
693.  A  pistil.  694.  Section  of  the  ovary,  showing  the  two  ascending  ovules.  695.  The  closed 
pod-shaped  receptacle  in  fruit.  696.  A  vertical  section  of  an  achenium,  showing  the  embryo 
of  the  seed.    697.  Cross-section  of  an  embryo,  showing  the  finely  convolute  cotyledons. 


416  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

from  the  leaves  and  fruit  of  a  Melaleuca  of  the  Moluccas.  Nu- 
merous Australian  species  of  Eucalyptus,  which  compose  a  great 
part  of  the  forests  of  that  country,  yield  a  large  quantity  of  tannin. 
The  aromatic  fruits  of  many  species,  filled  with  sugar  and  muci- 
lage, and  acidulated  with  a  free  acid,  are  highly  prized  ;  such,  for 
instance,  as  the  Pomegranate,  the  Guava,  Rose-Apple,  &lc. 

781.  Ord.  Melastomaceae.  Trees,  shrubs,  or  herbs,  with  opposite 
ribbed  leaves,  and  showy  flowers,  with  as  many  or  twice  as  many 
stamens  as  petals ;  the  anthers  mostly  appendaged  and  opening  by 
pores,  inflexed  in  sestivation  :  further  distinguished  from  Myrtacese 
by  the  leaves  not  being  dotted ;  and  from  Lythracese  by  the  adna- 
tion  of  the  calyx-tube  (at  its  nerves  at  least)  with  the  ovary.  — ^ 
Ex.  The  beautiful  species  of  Rhexia  represent  this  remarkable 
order  in  the  United  States :  all  the  rest  are  tropical.  The  berries 
of  Melastoma  are  eatable,  and  tinge  the  lips  black,  like  whortle- 
berries ;  whence  the  generic  name. 

782.  Ord.  lythracefB  (the  Loosestrife  Family)  is  distinguished 
among  these  perigynous  orders,  with  exalbuminous  seeds,  by  its 
tubular  calyx  inclosing  the  2  -  4-celled  ovary,  but  entirely  free  from 
it.  The  styles  are  perfectly  united  into  one  :  the  fruit  is  a  thin 
capsule.  The  stamens  are  inserted  on  the  tube  of  the  calyx  below 
the  petals.  —  Ex.  Ly thrum.    Chiefly  tropical,  of  little  consequence. 

783.  Ord.  Rhizophoracea;  {the  Mangrove  Family)  consists  of  a  few 
tropical  trees  (extending  into  Florida  and  Louisiana),  growing  in 
maritime  swamps ;  with  the  ovary  often  partly  free  from  the  ca- 
lyx, two-celled,  with  two  pendulous  ovules  in  each  cell ;  they  are 
remarkable  for  their  opposite  leaves,  with  interpetiolar  stipules, 
and  for  the  germination  of  the  embryo  while  within  the  pericarp 
(645).  —  Ex.  Rhizophora,  the  Mangrove  (Fig.  118).  The  astrin- 
gent bark  has  been  used  as  a  febrifuge,  and  for  tanning. 

784.  Ord.  CombretaceSB  consists  of  tropical  trees  or  shrubs  (which 
have  one  or  two  representatives  in  Southern  Florida),  often  apeta- 
lous,  but  with  slender  colored  stamens  ;  distinguishable  from  any 
of  the  preceding  orders  of  this  group  by  their  one-celled  ovary, 
with  several  suspended  ovules,  but  only  a  solitary  seed,  and  con- 
volute cotyledons.  —  Ex.  Combretum.  Some  species  cultivated 
for  ornament;  some  are  used  by  tanners.  The  seeds  of  Termina- 
lia  Catappa  (which  extends  into  Florida)  are  eaten  like  almonds. 

785.  Ord.  OnagraccSB  (the  Evening- Primrose  Family).  Herbs,  or 
rarely  shrubby  plants,  with  alternate  or  opposite  leaves,  not  dotted, 


THE    POLYPETALOUS    ORDERS. 


417 


nor  furnished  with  stipules.  Flowers  usually  showy,  tetramerous. 
Calyx  adherent  to  the  ovary,  and  usually  produced  beyond  it  into 
a  tube.  Petals  usually  four  (rarely  three  or  six,  occasionally  ab- 
sent), and  the  stamens  as  many,  or  twice  as  many,  inserted  into 
the  throat  of  the  calyx.  Ovary  commonly  four-celled  :  styles 
united ;  the  stigmas  four,  or  united  into  one.  Fruit  mostly  cap- 
sular. —  Ex.  Chiefly  an  American  order  ;  many  are  ornamental 
in  cultivation.  Fuchsia,  remarkable  for  its  colored  calyx  and  ber- 
ried fruit;  (Enothera  (Evening  Primrose) ;  Epilobium,  where  the 
seeds  bear  a  coma ;  Gaura,  where  the  petals  are  often  irregular  ; 
Ludwigia,  which  is  sometimes  apetalous  ;  and  Circsea,  where  the 
lobes  of  the  calyx,  petals,  stamens,  cells  of  the  ovary,  and  the 
seeds,  are  reduced  to  two ;  showing  a  connection  with  the  appended 


786.  Subord.  HalorageSB,  which  are  a  sort  of  reduced  aquatic 
Onagraceoe,  often  apetalous  :  the  solitary  seeds  furnished  with  a 
little  albumen,  as  in  Myriophyllum  (Water-Milfoil)  and  Hippuris 
(Horse-tail),  where  the  limb  of  the  calyx  is  almost  wanting;  the 
petals  none  ;  the  stamens  reduced  to  a  single  one,  and  the  ovary  to 
a  single  cell,  with  a  solitary  seed. 


FIG.  698.  Flower  of  CEnothera  frulicosa.  699.  The  same,  about  the  natural  size,  with  the 
petals  removed.  700.  Magnified  grains  of  pollen,  with  some  of  the  intermixed  cellular  threads. 
701.  Cross-section  of  the  four-lobed  and  four-celled  capsule. 

FIG.  702.  Hippuris  vulgaris  (suborder  Halorageae).  703.  Magnified  flower,  with  the  sub- 
tending leaf.    704.  Vertical  section  of  the  ovary.    705.  Vertical  section  of  the  fruit  and  seed. 


418 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


787.  Ord.  CactaceSB  (the  Cactus  Family).  Succulent  shrubby- 
plants,  peculiar  in  habit,  with  spinous  buds,  usually  leafless ;  the 
stems  either  subglobose  and  many -angled,  columnar  with  several 
angles,  or  flattened  and  jointed.  Flowers  usually  large  and  showy. 
Calyx  of  numerous  sepals,  imbricated,  coherent  with  and  crowning 
the  one-celled  ovary,  or  covering  its  whole  surface  ;  the  inner  usu- 
ally confounded  with  the  indefinite  petals.  Stamens  indefinite, 
with  long  filaments,  cohering  with  the  base  of  the  petals.  Styles 
united :  stigmas  and  parietal  placentae  several.  Fruit  a  berry. 
Seeds  numerous,  with  little  or  no  albumen. —  All  American,  the 
greater  part  Mexican  or  on  the  borders  of  Mexico.  The  common 
Opuntia  (Prickly  Pear)  extends  north  to  New  England.  The  mu- 
cilaginous fruit  is  eatable. 

788.  Ord,  GroSSUlaceSB  {the  Gooseberry  Family).  Small  shrubs, 
either  spiny  or  prickly,  or  unarmed;  with  alternate,  palmately 
lobed  and  veined  leaves,  usually  in  fascicles,  often  sprinkled  with 


resinous  dots.     Flowers  in  racemes  or  small  clusters.     Calyx-tube 


FIG.  706.  The  Gooseberry  (Ribes  Uva-crispa) ;  a  branch  in  flower.  707.  Branch  in  fruit. 
708.  The  calyx,  bearing  the  petals  and  stamens,  cut  away  from  the  summit  of  the  ovary  (709), 
and  laid  open.  710,  711.  Sections  of  the  unripe  fruit.  712.  Magnified  seed  (anairopous). 
713.  The  same  from  the  ripe  fruit,  where  the  raphe  separates  from  the  side  of  the  seed,  and 
forms  a  part  of  the  funiculus.  714.  Longitudinal  section  of  the  same,  showing  the  minute  em- 
bryo at  the  extremity  of  the  alburhen. 


THE  POLYPETALOUS  ORDERS.  419 

adherent  to  the  one-celled  ovary,  and  more  or  less  produced  be- 
yond it,  five-lobed,  sometimes  colored.  Petals  (small)  and  stamens 
five,  inserted  on  the  calyx.  Ovary  with  two  parietal  placentae : 
styles  more  or  less  united.  Fruit  a  many-seeded  berry,  crowned 
with  the  shrivelled  remains  of  the  flower.  Embryo  minute,  in 
hard  albumen.  —  Ex,  Ribes  (Gooseberry  and  Currant).  Natives 
of  temperate  and  colder  regions,  chiefly  of  the  northern  hemi- 
sphere. Never  unwholesome  :  the  fruit  usually  esculent,  contain- 
ing mucilaginous  and  saccharine  pulp,  with  more  or  less  malic  or 
citric  acid.  Several  Oregon  and  Californian  species  are  showy  in 
cultivation. 

789.  Ord.  Loasacese.  Herbs  usually  clothed  with  rigid  or  sting- 
ing hairs ;  the  leaves  opposite  or  alternate,  without  stipules ;  the 
flowers  showy.  Calyx-tube  adherent  to  the  one-celled  ovary  ;  the 
limb  mostly  five-parted.  Petals  as  many,  or  twice  as  many,  as  the 
lobes  of  the  calyx.  Stamens  perigynous,  indefinite,  and  in  several 
parcels,  or  sometimes  definite.  Style  single.  Ovary  with  three 
to  five  parietal  placentae.  Seeds  few  or  numerous,  albuminous.  — 
Ex.  Loasa,  Mentzelia,  Cevallia  ;  the  latter  with  solitary  seeds  and 
no  albumen.  All  American,  and  in  the  United  States  nearly  con- 
fined to  the  regions  beyond  the  Mississippi.  The  bristles  of  Loasa 
sting  like  nettles. 

790.  Ord.  Tumeracefe.  Herbs,  with  the  habit  of  Cistus  or  Heli- 
anthemum  ;  the  alternate  leaves  without  stipules.  Flowers  solita- 
ry, showy.  Calyx  five-lobed  ;  the  five  petals  and  five  stamens  in- 
serted on  its  throat.  Ovary  free  from  the  calyx,  one-celled,  with 
three  parietal  placentae.  Styles  distinct,  commonly  branched  or 
many-cleft  at  the  summit.  Fruit  a  three-valved  capsule.  Seeds' 
numerous  (anatropous),  with  a  crustaceous  and  reticulated  testa, 
and  a  membranaceous  aril  on  one  side.  Embryo  in  fleshy  albu- 
men.—  Ex.  Turnera,  of  which  there  is  one  species  in  Georgia. 

791.  Ord.  PassifloraceSB  {the  Passion-flower  Family),  Herbs,  or 
somewhat  shrubby  plants,  climbing  by  tendrils;  with  alternate,  en- 
tire, or  palmately  lobed  leaves,  mostly  furnished  with  stipules. 
Flowers  often  showy,  sometimes  involucrate.  Calyx  mostly  of 
five  sepals,  united  below,  free  from  the  one-celled  ovary ;  the 
throat  bearing  five  petals  and  a  filamentous  crown.  Stamens  as 
many  as  the  sepals,  monadelphous,  and  adhering  to  the  stalk  of 
the  ovary,  which  has  usually  three  club-shaped  styles  or  stigmas, 
and  as  many  parietal  placentae.     Fruit  mostly  fleshy  or  berry-like. 


420  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Seeds  numerous,  with  a  brittle  sculptured  testa,  inclosed  in  pulp. 
Embryo  inclosed  in  thin,  fleshy  albumen.  —  Ex.  Passiflora  (the 
Passion-flower,  Granadilla) :  nearly  all  natives  of  tropical  Amer- 
ica. Two  species  are  found  as  far  north  as  Virginia  and  Ohio. 
Many  are  cultivated  for  their  singular  and  showy  flowers.  The 
acidulous  refrigerant  pulp  of  Passiflora  quadrangularis  (the  Grana- 
dilla), P.  edulis,  and  others,  is  eaten  in  the  West  Indies,  &c.  But 
the  roots  are  emetic,  narcotic,  and  poisonous.  They  contain  a 
principle  resembling  morphine,  which,  in  some  species,  extends 
even  to  the  flowers  and  fruit. 

792.  Ord.  Papayaceffi  comprises  merely  a  small  genus  of  tropical 
dioBcious  trees,  of  peculiar  character :  the  principal  one  is  the  Pa- 
paw-tree  (Carica  Papaya)  of  tropical  America,  which  has  been 
introduced  into  East  Florida.  The  fruit,  when  cooked,  is  eatable  ; 
but  the  juice  of  the  unripe  fruit,  as  well  as  of  other  parts  of  the 
plant,  is  a  powerful  vermifuge.  The  juice  contains  so  much  fibrine 
that  it  has  an  extraordinary  resemblance  to  animal  matter :  meat 
washed  in  water  impregnated  with  this  juice  is  rendered  tender ; 
even  the  exhalations  from  the  tree  produce  the  same  effect  upon 
meat  suspended  among  the  leaves. 

793.  Ord.  Cucurbitacea;  {the  Gourd  Family).  Juicy  herbs,  climb- 
ing by  tendrils ;  with  alternate,  palmately  veined  or  lobed,  rough 
leaves,  and  monoecious  or  dioecious  flowers.  Calyx  of  four  or  five 
(rarely  six)  sepals,  united  into  a  tube,  and  in  the  fertile  flowers 
adherent  to  the  ovary.  Petals  as  many  as  the  sepals,  commonly 
more  or  less  united  into  a  monopetalous  corolla,  which  coheres 
with  the  calyx.  Stamens  five  or  three,  inserted  into  the  base  of 
the  corolla  or  calyx,  either  distinct  or  variously  united  by  their  fila- 
ments, and  long,  sinuous  or  contorted  anthers.  Ovary  two  to  five- 
celled  (rarely  one-celled  by  obliteration,  and  even  one-ovuled)  ; 
the  thick  and  fleshy  placentae  often  filling  the  cells,  or  diverging 
before  or  after  reaching  the  axis  and  carried  back  so  as  to  reach 
the  walls  of  the  pericarp,  sometimes  manifestly  parietal ;  the  dis- 
sepiments often  disappearing  during  its  growth :  stigmas  thick, 
dilated  or  fringed.  Fruit  (pepo,  613)  usually  fleshy,  with  a  hard 
rind,  sometimes  membranous.  Seeds  mostly  flat,  with  no  albu- 
men. Embryo  straight.  Cotyledons  foliaceous.  —  £^a?.  The  Pump- 
kin and  Squash  (Cucurbita),  Gourd,  Cucumber,  and  Melon.  When 
the  acrid  principle  which  prevails  throughout  the  order  is  greatly 
diffused,  the  fruits  are  ratable  and  sometimes  delicious  :  when  con- 


THE  POLYPETALOUS  ORDERS. 


421 


centrated,  as  in  the  Bottle  Gourd,  Bryony,  &c.,  they  are  danger- 
ous or  actively  poisonous.  The  officinal  Colocynth^  a  resinoid,  bit- 
ter extract  from  the  pulp  of  Cucumis  Colocynthis  (of  the  Levant, 
India,  ^c),  is  very  acrid  and  poisonous;  and  Elaterium,  obtained 
from  the  juice  of  the  Squirting  Cucumber  (Momordica  Elaterium 
of  the  South  of  Europe),  is  still  more  violent  in  its  effects.  Mo- 
mordica Balsamina  (the  cultivated  Balsam- Apple)  contains  the 
same  principle  in  smaller  quantity.     The  seeds  of  all  are  harmless. 


794.  Ord.  Crassulaceae  (the  Orpine  Family).  Herbs,  or  slightly 
shrubby  plants,  mostly  fleshy  or  succulent ;  with  scattered  leaves, 
and  flowers  usually  in  cymes  or  racemes.  Calyx  of  three  to 
twenty  sepals,  more  or  less  united  at  the  base,  free  from  the  ova- 
ries, persistent.  Petals  as  many  as  the  sepals,  rarely  combined 
into  a  monopetalous  corolla.  Stamens  as  many  or  twice  as  many 
as  the  sepals,  inserted  with  the  petals  on  the  base  of  the  calyx. 
Pistils  always  as  many  as  the  sepals,  distinct,  or  rarely  (in  Pentho- 
rum  and  Diamorpha)  partly  united  :  ovaries  becoming  follicles  in 
fruit,  several-seeded.  Embryp  straight,  in  thin  albumen.  —  Ex. 
Sedum  (Stone-crop,  Orpine,  Live-for-ever),  Crassula,  Sempervi- 
vum,  or  Houseleek,  &c.  Distinguished  by  their  completely  sym- 
metrical flowers,  on  which  account  they  have  already  been  illus- 
trated (449,  450).  They  mostly  grow  in  arid  places  :  of  no  eco- 
nomical importance. 


FIG.  715.  Staminate  flower  of  the  Gourd ;  the  calyx  and  corolla  cut  away.  716.  Cross-sec- 
tion of  the  united  antliers.  718.  Separate  stamen  of  the  Melon.  719.  Section  of  the  ovary  of 
the  Gourd.    720.  Plan  of  one  of  the  three  constituent  carpels. 

36 


428 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


795.  Ord.  SaxifragaceSB  (the  Saxifrage  Family).  Herbs  or  shrubs, 
with  alternate  or  opposite  leaves.  Calyx  of  four  or  five  more  or 
less  united  sepals,  either  free  from  or  more  or  less  adherent  to  the 
ovary,  persistent.  Petals  as  many  as  the  sepals,  rarely  wanting. 
Stamens  as  many,  commonly  twice  as  many,  or  rarely  three  or 
four  times  as  many,  as  the  sepals,  perigynous.  Ovaries  mostly 
two  (sometimes  three  or  four),  usually  united  below  and  distinct  at 
the  summit.  Seeds  numerous,  with  a  straight  embryo  in  fleshy 
albumen.  There  are  three  principal  divisions,  or  suborders ; 
namely  : 


796.  Subord.  SaxifrageSB  {the  true  Saxifrage  Family).  Herbs. 
Petals  imbricate  in  aestivation.  Capsule  (when  the  carpels  are 
united),  either  two-celled  with  the  placentae  in  the  axis,  or  one- 
celled  with  parietal  placentae.  —  Eix.  Saxifraga,  Sullivantia  (Fig. 
721),  Heuchera.  Of  little  consequence,  except  as  ornamental 
plants.  The  roots  are  generally  astringent ;  powerfully  so  in  Heu- 
chera, especially  in  the  common  H.  Americana  (sometimes  called 
Alum-root). 

FIG.  721.  Sullivantia  Ohionis.  722.  Flower  with  the  calyx  laid  open,  somewhat  enlarged. 
723.  Fruit  surrounded  by  the  persistent  calyx  and  withered  petals,  enlarged.  724.  Section  of 
the  lower  part  of  the  capsule,  magnified;  showing  the  central  placenta  covered  with  the  as- 
cending seeds.  725.  A  magnified  seed,  with  its  cellular,  wing-like  testa.  726.  Section  of  the 
nucleus,  showing  the  embryo  in  the  midst  of  albumen. 


THE  POLYPETALOUS  ORDERS.  423 

797.  Subord.  Hydrangea  {the  Hydrangea  Family).  Shrubs.  Pet- 
als valvate  in  aestivation.  Capsule  two-  (rarely  five-  to  ten-)  celled  : 
the  styles  or  stigmas  distinct  or  united.  Stamens  sometimes  nu- 
merous.—  Ex.  Hydrangea,  Decumaria. 

798.  Subord.  Philadelphefe  {the  Mock  Orange  Family).  Shrubs. 
Petals  convolute  in  aestivation.  Capsule  three-  or  four-celled : 
styles  more  or  less  united.  Stamens  mostly  numerous. — Ex. 
Philadelphus,  the  Mock  Orange. 

799.  Ord.  HamamelaceflB  {the  Witch-Hazel  Family).  Shrubs  or 
small  trees,  with  alternate  simple  leaves,  without  stipules.  Flow- 
ers often  polygamous.  Petals  valvate  in  aestivation.  Stamens 
twice  as  many  as  the  petals,  half  of  them  sterile  ;  or  numerous, 
and  the  petals  none.  Summit  of  the  ovary  free  from  the  calyx,  a 
single  ovule  suspended  from  the  summit  of  each  cell :  styles  two, 
distinct.  Capsules  cartilaginous  or  bony.  Seeds  bony,  with  a 
small  embryo  in  hard  albumen.  —  Ex.  Hamamelis  (Witch-Hazel), 
Fothergilla.  A  small  order,  of  little  importance.  Hamamelis  is 
remarkable  for  flowering  late  in  autumn,  just  ae  its  leaves  are 
falling,  and  perfecting  its  fruit  the  following  spring. 

800.  Ord.  UmbelliferSB  {the  Parsley  Family).  Herbs,  with  hollow 
stems,  and  alternate,  dissected  leaves,  with  the  petioles  sheathing 
or  dilated  at  the  base.  Flowers  in  simple  or  mostly  compound 
umbels,  which  are  occasionally  contracted  into  a  kind  of  head. 
Calyx  entirely  coherent  with  the  surface  of  the  dicarpellary  ovary  ; 
its  limb  reduced  to  a  mere  border,  or  to  five  small  teeth.  Petals 
five,  valvate  in  aestivation,  inserted,  with  the  five  stamens,  on  a  disk 
which  crowns  the  ovary  ;  their  points  inflexed.  Styles  two ;  their 
bases  often  united  and  thickened,  forming-  a  stylopodium.  Fruit 
dry,  separating  from  each  other,  and  often  from  a  slender  axis 
{carpophore)^  into  two  indehiscent  carpels  (called  mericarps)  :  the 
faces  by  which  these  cohere  receive  the  technical  name  of  com- 
missure: they  are  marked  with  a  definite  number  of  ribs  {juga), 
which  are  sometimes  produced  into  wings :  the  intervening  spaces 
{intervals),  as  well  as  the  commissure,  sometimes  contain  canals 
or  receptacles  of  volatile  oil,  called  inttcB:  these  are  the  principal 
terms  peculiarly  employed  in  describing  the  plants  of  this  difficult 
family.  Embryo  minute.  Albumen  hard  or  corneous.  —  Ex.  The 
Carrot,  Parsnip,  Celery,  Caraway,  Anise,  Coriander,  Poison  Hem- 
lock, &;c.,  are  common  representatives  of  this  well-known  family. 
Nearly  all  Umbelliferous  plants  are  furnished  with  a  volatile  oil  or 


424 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


balsam,  chiefly  accumulated  in  the  roots  and  in  the  reservoirs  of 
the  fruit,  upon  which  their  aromatic  and  carminative  properties 
depend :  sometimes  it  is  small  in  quantity,  so  as  merely  to  flavor 
the  saccharine  roots  which  are  used  for  food  ;  as  in  the  Carrot  and 
Parsnip.  But  in  many  an  alkaloid  principle  exists,  pervading  the 
foliage,  stems,  and  roots,  especially  the  latter,  which  renders  them 


acrid-narcotic  poisons.  And  finally,  many  species  of  warm  re- 
gions yield  odorous  gum-resins  (such  as  Galbanum,  Assafoetida, 
&c.),  which  have  active  stimulant  properties.  The  stems  of  Cel- 
ery (Apium  graveolens),  which  are  acrid  and  poisonous  when  the 
plant  grows  wild  in  marshes,  &c.,  are  rendered  innocent  by  culti- 
vation in  dry  ground,  and  by  blanching.  Among  the  virulent 
acrid-narcotic  species,  the  most  famous  are  the  Hemlock  (Conium 
maculatum,  naturalized  in  this  country),  and  Cicuta  maculata 
(Cowbane,  Water-Hemlock)  indigenous  to  this  country,  the  root 
of  which  (like  that  of  the  C.  virosa  of  Europe)  is  a  deadly  poi- 


FIG.  727.  Conium  maculatum  (Poison  Hemlock),  a  portion  of  the  spotted  stem,  with  a  leaf; 
and  an  umbel  with  young  fruit.  728.  A  flower  umbellet.  729.  A  flower,  enlarged.  730.  The 
fruit.  731.  Cross-section  of  the  same,  showing  the  involute  (ccElospermous)  albumen  of  the 
two  seeds.  732.  Longitudinal  section  of  one  mericarp,  exhibiting  the  minute  embryo  near  the 
apex  of  the  albumen. 


THE    POLYPETALOUS    ORDERS. 


425 


son.     A  drachm  of  the  fresh  root  has  killed  a  boy  in  less  than 
two  hours. 


801.  Ord.  AraliaceOB  (the  Spikenard  Family).  A  small  family, 
scarcely  differing  from  Umbelliferpe  in  botanical  character,  except 
that  the  ovary  is  mostly  composed  of  more  than  two  carpels,  which 
do  not  separate  when  ripe,  but  become  drupes  or  berries  ;  and 
the  albumen  is  not  hard  like  horn,  but  only  fleshy.  —  Ex.  Aralia 
(the  Spikenard,  the  Wild  Sarsaparilla,  and  the  Angelica-tree), 
Panax  (Ginseng),  and  Hedera  (the  Ivy).  Their  properties  are 
aromatic,  stimulant,  somewhat  tonic,  and  alterative. 


802.  Ord.  CornaceSB  {the  Cornel  Family).  Chiefly  trees  or  shrubs  ; 
with  the  leaves  almost  always  opposite,  destitute  of  stipules.  Flow- 
ers in  cymes,  sometimes  in  heads  surrounded  by  colored  involu- 
cres.    Calyx  coherent  with  the  two-celled  ovary ;  the  very  small 

FIG.  733.  Flower  of  Osmorrhiza  longistylis.  734.  Umbel  of  the  same  in  fruit :  a,  the  invo- 
lucels.  735.  The  ripe  mericarps  separating  from  the  axis  or  carpophore.  736.  Cross-section 
of  the  fruit  of  Angelica,  where  the  lateral  ribs  are  produced  into  wings:  the  black  dots  repre- 
sent the  vittae,  as  they  appear  in  a  cross-section.  737.  One  of  the  mericarps  of  the  same,  show- 
ing the  inner  face,  or  commissure,  as  well  as  the  transverse  section,  with  two  of  the  vittae,  a. 

FIG.  738,  Flower  of  Aralia  nudicaulis  (Wild  Sarsaparilla) ;  a  vertical  section,  displaying 
two  of  the  cells  of  the  ovary.  739.  Cross-section  of  the  ovary.  740.  Longitudinal  section  of  a 
eeed,  magnified,  showing  the  small  embryo  at  the  upper  end. 

36* 


426  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

limb  four-toothed.  Petals  four,  valvate  in  aestivation.  Stamens 
four,  alternate  with  the  petals.  Styles  united  into  one.  Fruit  a 
two-celled  drupe.  —  Ex.  Cornus,  the  Dogwood.  Chiefly  remark- 
able for  their  bitter  and  astringent  bark,  which  in  this  country  has 
been  substituted  for  Cinchona.  The  peculiar  principle  they  con- 
tain is  named  Cornine.  Cornus  Canadensis  (Fig.  240)  is  a  low 
and  herbaceous  species. 


Division    II.  —  Monopetalous    or    Gamopetalous    Exogenous 

Plants.* 

Floral  envelopes  consisting  of  both  calyx  and  corolla  :  the  petals 
more  or  less  united  (corolla  gamopetalous). 

Conspectus  of  the  Orders. 

Group  1.  Ovary  coherent  with  the  calyx,  two-  to  several-celled,  with  one  or 
many  ovules  in  each  cell  Seeds  albuminous,  with  a  small  embryo.  Sta- 
mens inserted  on  the  corolla.  —  Leaves  opposite. 

Stipules  wanting.  Caprifoliace.e,  p.  428. 

Stipules  interpetiolar  (or  leaves  whorled).  Rubiace^,  p.  429. 

Group  2.  Ovary  coherent  with  the  calyx,  one-celled  and  one-ovuled;  rarely 
three-celled  with  two  of  the  cells  empty.  Seeds  with  little  or  no  albu- 
men. Stamens  inserted  on  the  corolla.  Calyx  a  mere  ring,  crown,  or 
pappus,  or  obsolete.     Fruit  like  an  achenium. 

Stamens  distinct.     Seed  suspended. 

Stamens  3  or  fewer.  VALERiANACEiE,  p.  431. 

Stamens  4.     Heads  involucrate.  Dipsace^,  p.  432. 

Stamens  syngenesious.     Seed  erect.  Compositje,  p.  433. 

Group  3.  Ovary  coherent  with  the  calyx,  with  two  or  more  cells  and  numer- 
ous ovules.  Seeds  albuminous.  Stamens  inserted  with  the  corolla  (epi- 
gynous) ;  anthers  not  opening  by  pores. 

Corolla  irregular.     Stamens  united  in  a  tube.  Lobeliace^,  p.  435. 

Corolla  regular.     Stamens  distinct.  Campanulace^,  p.  436. 

Group  4.  Ovary  free  from  the  calyx,  or  sometimes  coherent  with  it,  with 
two  or  more  cells  and  numerous  ovules.  Seeds  albuminous.  Stamens 
inserted  with  the  corolla,  or  rarely  coherent  with  its  base,  as  many,  or 
twice  as  many,  as  its  lobes  :  anthers  mostly  opening  by  pores  or  chinks. 

*  CucurbitacesB,  placed  in  the  Polypetalous  series,  are  commonly  somewhat 
gamopetalous:  so  are  some  exotic  Crassulaceae,  &c. 


THE    MONOPETALOUS    ORDERS.  427" 

Anthers  two-celled.  ERicACEiE,  p.  436. 

Anthers  one-celled.  Epacridaceje,  p.  439. 

Group  5.  Ovary  free,  or  rarely  coherent  with  the  calyx,  several-celled,  with 
a  single  ovule  (or  at  least  a  single  seed)  in  each  cell.  Seeds  mostly  albu- 
minous. Stamens  definite,  as  many  as  the  lobes  of  the  (sometimes  almost 
polypetalous)  corolla  and  alternate  with  them,  or  two  to  four  times  as 
many  :  anthers  not  opening  by  pores.  —  Trees  or  shrubs. 

Stamens  as  many  as  the  lobes  of  the  corolla  and  alternate  with  them. 

Aquifoliaceje,  p.  439. 
Stamens  more  numerous  and  all  fertile. 

Flowers  polygamous  :  calyx  free.  Ebenaceje,  p.  439. 

Flowers  perfect :  calyx  more  or  less  adnate.  Styracaceje,  p.  440. 

Stamens  as  many  fertile  as  there  are  lobes  of  the  corolla  and  opposite  them ; 

and  with  a  sterile  series  alternate  with  them.  SAPOTACEiE,  p.  440. 

Group  6.  Ovary  free,  or  with  the  base  merely  coherent  with  the  tube  of  the 
calyx,  one-celled,  with  a  free  central  placenta.  Stamens  inserted  into  the 
regular  corolla  opposite  its  lobes !  which  they  equal  in  number.  Seeds 
albuminous. 

Shrubs  or  trees :  fruit  drupaceous.  Myrsinace^s:,  p.  440. 

Herbs:  fruit  capsular.  PRiMULACEiE,  p.  440.. 

Group  7.  Ovary  free,  one-celled  with  a  single  ovule;  or  two-celled  with 
several  ovules  attached  to  a  thick  central  placenta.  Stamens  as  many  as 
the  lobes  of  the  regular  corolla  or  the  nearly  distinct  petals.  Seeds  albu- 
minous. 

Ovary  two-celled:  style  single  :  stamens  4.  PLAUTAGiNACE^ffi,  p.  441. 

Ovary  one-celled:  styles  and  stamens  5.  PLUftiBAGiNACE^,  p.  442. 

Group  8.     Ovary  free,  one-  or  two-  (or  spuriously  four-)  celled,  with  numer- 
ous ovules.     Corolla  bilabiate  or  irregular  ;  the  stamens  inserted  upon  its 
tube,  and  mostly  fewer  than  its  lobes. 
Ovary  one-celled  with  a  central  placenta.     Stam.  2.     Lentibulace^,  p.  443. 
Ovary  one-celled  with  parietal  placentae.  Orobanchaceje,  p.  443. 

Ovary  spuriously  4-5-celled  :  seeds  exalbuminous.   Subord.  Sesame^e,  p.  444. 
Ovary  two-celled:  placentae  in  the  axis. 

Seeds  indefinite,  winged:  albumen  none.  BignoniacejE,  p.  444. 

Seeds  few,  wingless:  albumen  none.     Corolla  convolute  in  aestivation. 

Acanthace^,  p.  444. 
Seeds  mostly  indefinite :  albumen  copious.     Corolla  imbricative  in  aestiva- 
tion. Scrophulariace^,  p.  445. 

Group  9.  Ovary  free,  two-  to  four-lobed,  and  separatin^r  or  splitting  into  as 
many  one-seeded  nuts  or  achenia,  or  drupaceous.  Corolla  regular  or  ir- 
regular; the  stamens  inserted  on  its  tube,  equal  in  number  or  fewer  than 
its  lobes.     Albumen  little  or  none. 

Stamens  4,  didynamous,  or  2.     Corolla  more  or  less  irregular. 

Ovary  not  4-lobed.  Verbenace^,  p.  446. 


428  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Ovary  4-lobed,  forming  4  achenia.  Labiat^e,  p,  447. 

Stamens  5.     Flower  regular.     Leaves  alternate.  Boraginaceje,  p.  448. 

Group  10.  Ovary  free,  compound,  or  the  carpels  two  or  more  and  distinct : 
the  ovules  usually  several  or  numerous.  Corolla  regular  ;  the  stamens 
inserted  upon  its  tube,  as  many  as  the  lobes  and  alternate  with  them. 
Seeds  albuminous. 

*  Ovary  compound  (of  two  or  more  united  carpels). 
Placentae  2,  parietal  (sometimes  expanded).     Embryo  minute. 

Corolla  not  valvate  in  sestivation. 

Leaves  lobed,  mostly  alternate      Seeds  few.    HYDROPHYLLACE^a:,  p.  449. 
Leaves  entire,  opposite.     Seeds  indefinite.  Gentianace^,  p.  454. 

Corolla  valvate-induplicate  in  aestivation.  Subord.  Menyanthide^s:,  p.  454. 
Placentae  in  the  axis  :  ovary  2-3-celled. 

Embryo  large,  bent  or  coiled,  with  little  albumen.     Seeds  one  or  two  in 
each  cell.  Convolvulace.*:,  p.  451. 

Embryo  straight  or  arcuate,  in  copious  albumen. 

Styles  2,  distinct.     Seeds  indefinite.  Hydroleace^e,  p.  450. 

Styles  united  nearly  or  quite  to  the  summit. 

Ovary  3-celled.  Cor.  convolute  in  aestivation.  Polemoniaceje,  p.  450. 
Ovary  3-celled.  Cor.  imbricated  in  aestivation.  Diapensiace^e,  p.  450. 
Ovary  2-celled.     Corolla  plaited  or  valvate  in  aestivation. 

SOLANACE^S,  p.  453. 

*  *  Ovaries  mostly  two  and  distinct,  at  least  in  fruit. 

Anthers  introrse  :  pollen  granular.  Apocynace-e,  p.  455. 

Anthers  extrorse  :  pollen  in  waxy  masses.  Asclepiadace.*:,  p.  455. 

Group  n.  Ovary  free,  two-celled,  few-ovuledj  the  cells  of  the  fruit  one- 
seeded.  Corolla  regular  (sometimes  nearly  polypetalous  or  wanting)  ;  the 
stamens  (two)  fewer  than  its  lobes.  —  Shrubs  or  trees. 

Seeds  erect.    Cor.  imbricated  or  contorted  in  aestivation.     Jasminace^s,  p.  456. 
Seeds  suspended.     Corolla  valvate  in  aestivation.  Oleace^s:,  p.  457. 

803.  Ord.  Caprifoliacese  (the  Honeysuckle  Family).  Mostly  shrubs, 
often  twining,  with  opposite  leaves,  and  no  stipules.  Calyx-tube 
adnate  to  the  2-5-celled  ovary;  the  limb  4-5-cleft.  Corolla 
regular  or  irregular.  Stamens  inserted  on  the  corolla,  as  many  as 
the  petals  of  which  it  is  composed,  and  alternate  with  them,  or 
rarely  one  fewer.  Fruit  mostly  a  berry  or  drupe.  Seeds  pendu- 
lous, albuminous.  —  Ex.  The  Honeysuckles  (Lonicera),  which 
have  usually  a  peculiar  bilabiate  corolla  (470,  Fig.  743),  the 
Snowberry  (Symphoricarpus),  Diervilla,  which  has  a  capsular 
fruit,  &c.,  compose  the  tribe  Lonicere^,  characterized  by  their 
tubular  flowers  and  filiform  style :  while  the  Elder  (Sambucus) 
arid  Viburnum,  which  have  a  rotate  or  urn-shaped  corolla,  form 
the  tribe  Sambuce^.     These  plants  chiefly  belong  to  temperate 


THE    MONOPETALOUS    ORDERS. 


429 


regions.  Several  are  widely  cultivated  for  ornament.  They  are 
generally  bitter,  and  rather  active  or  nauseous  in  their  proper- 
ties :  but  the  fruit  of  some  few  is  edible. 


804.  Ord.  Rubiacese  {the  Madder  Family),  Shrubs  or  trees,  or 
often  herbs,  with  the  entire  leaves  either  in  whorls,  or  opposite 
and  furnished  with  stipules.  Calyx-tube  completely,  or  rarely  in- 
completely, adnate  to  the  2  -  5-celled  ovary  ;  the  limb  four-  or  five- 
cleft  or  toothed,  or  occasionally  obsolete.  Stamens  as  many  as 
the  lobes  of  the  regular  corolla,  and  alternate  with  them,  inserted 
on  the  tube.  Fruit  various.  Seeds  albuminous.  —  This  extensive 
family  divides  into  two  suborders,  to  which  a  third  may  be  ap- 
pended, which  differs  in  the  free  ovary,  and  is  by  most  botanists 
deemed  a  distinct  order. 

805.  Subord.  StellateSD  (the  true  Madder  Family).  Herbs,  with 
the  leaves  in  whorls ;  but  all  except  a  single  pair  are  generally 
supposed  to  take  the  place  of  stipules.  —  Ex.  Galium,  Rubia  (the 
Madder),  &c.,  nearly  all  belonging  to  the  colder  parts  of  the  world. 

806.  Subord.  CinchoneaB  (the  Peruvian- Bark  Family).  Shrubs, 
trees,  or  herbs ;  the  leaves  opposite  and  furnished  with  stipules, 
which  are  very  various  in  form  and  appearance.  —  Ex.  Cephalan- 

FIG.  741.  Branch  of  Lonicera  (Xylosteon)  oblongifolia:  the  two  ovaries  united!  742.  Lo- 
nicera  (Caprifolium)  parviflora.  743.  A  flower  about  the  natural  size.  744.  Longitudinal  sec- 
tion of  the  ovary.  745.  Longitudinal  section  of  a  magnified  seed,  showing  the  albumen  and 
minute  embryo. 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


thus  (Button-bush),  Hedyotis,  and  an  immense  number  of  tropical 
genera.     Their  stipules  distinguish  them  from  Caprifoliacese. 

807.  Subord.  Loganiea;,  or  Spigeliece,  have  opposite  stipulate  leaves, 
and  the  ovary  nearly  or  entirely  free  from  the  persistent  calyx.  — 
Ex.  Mitreola,  Spigelia  (the  Pink-root),  and  other  genera  interme- 
diate between  Rubiaceae  and  Apocynacese. 

808.  Very  active,  and  generally  febrifugal  properties  prevail  in 
this  large  order.  The  roots  of  Madder  yield  a  most  important 
dye:  and  many  Galiums  have  a  similar  red  coloring  matter. — 


The  division  Cinchoness  furnishes  two  of  the  most  valuable  known 
remedial  agents,  namely,  Peruvian  hark,  or  CincJiona,  and  Ipecac- 
uanha. The  febrifugal  properties  of  the  former  depend  on  the 
presence  of  two  alkalis,  Cinchonia  and  Quinia,  both  combined 
with  Kinic  acid.  The  Quinquina  harks,  which  are  derived  from 
some  species  of  Exostemma  and  other  West  Indian,  Mexican,  and 
Brazilian  genera,  contain  neither  cinchonia  nor  quinia.  The  bark 
of  Pinckneya  pubens,  of  the  Southern  United  States,  has  been  sub- 
stituted for  Cinchona.  —  The  true  Ipecacuanha  is  furnished  by  the 
roots  of  Cephaselis   Ipecacuanha  of  Brazil   and  the  mountains  of 

FIG.  746.  Piece  of  Rubia  tinctoria  (the  Madder)  in  flower.  747.  The  fruit.  748.  The  two 
constituent  portions  of  the  fruit  separating.  749.  Vertical  section  of  one  carpel,  showing  the 
curved  embryo.     750.  Section  of  a  flower  of  Galium. 

FIG.  751.  Cephalanthus  occidentaJis,  the  Button-bush.  752.  A  flower,  taken  from  the  head. 
753.  The  corolla  laid  open. 


THE    MONOPETALOUS    ORDERS. 


431 


New  Granada.  Its  emetic  principle  (called  Emetine)  also  exists 
in  Psychotria  emetica  of  New  Granada,  which  furnishes  the  striat- 
ed, black,  or  Peruvian  Ipecacuanha.  Coffee  is  the  horny  seed 
(albumen)  of  CofFsea  Arabica.  According  to  Blume,  the  leaves 
of  the  Coffee-plant  are  used  as  a  substitute  for  tea  in  Java.  —  The 
roots  and  leaves  of  Spigelia  Marilandica  (Carolina  Pink-root),  form 
a  well-known  vermifuge. 


809.  Ord,  Yaleriauaceae  (the  Valerian  Family).  Herbs  with  op- 
posite leaves,  and  no  stipules.  Flowers  often  in  cymes,  panicles, 
or  heads.  Limb  of  the  adnate  calyx  two-  to  four-toothed,  obsolete, 
or  else  forming  a  kind  of  pappus.  Corolla  tubular  or  funnel-form, 
sometimes  with  a  spur  at  the  base,  four-  or  five-lobed.  Stamens 
distinct,  inserted  on  the  corolla,  usually  fewer  than  its  lobes. 
Ovary  one-ovuled,  with  one  perfect  cell  and  two  abortive  ones. 
Fruit  a  kind  of  achenium.  Seed  suspended,  exalbuminous.  Em- 
bryo straight.  Radicle  superior.  —  Ex.  Valeriana,  the  Valerian ; 
Fedia,  the  Lamb-lettuce  :  the  latter  is  eaten  as  a  salad.  The 
roots,  &c.,  of  the  perennial  species  exhale  a  heavy  and  peculiar 

FIG.  754.  Hedyotis  (Houstonia)  caerulea.  755,  756.  The  two  sorts  of  flowers  that  different 
individuals  bear,  with  the  corolla  laid  open ;  one  with  the  stamens  at  the  base,  the  other  at  the 
summit  of  the  tube:  the  lower  figure  shows  also  a  section  of  the  ovary.  757,  Cross-section  of 
an  anther,  magnified.  758.  Anther  less  enlarged,  opening  longitudinally.  759.  Capsule  with 
the  calyx.  760,  761.  Views  of  the  capsule  in  dehiscence.  762.  Diagram  of  a  cross-section  of 
the  unexpanded  flower. 


432 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


odor,  have  a  somewhat  bitter,  acrid  taste,  and  are  antispasmodic 
and  vermifugal.  The  Valerian  of  the  shops  is  chiefly  derived 
from  Valeriana  officinalis  of  the  South  of  Europe.  It  produces  a 
peculiar  intoxication  in  cats.  The  roots  of  V.  edulis  are  used  for 
food  by  the  aborigines  of  Oregon.  The  Spikenard  of  the  ancients, 
esteemed  as  a  stimulant  medicine  as  well  as  a  perfume,  is  the  root 
of  Nardostachys  Jatamansi  of  the  mountains  of  the  North  of  India. 


810.  Ord.  DipsaceSB  (the  Teasel  Family).  Herbs,  with  opposite 
or  whorled  sessile  leaves,  destitute  of  stipules.  Flowers  in  dense 
heads,  which  are  surrounded  by  an  involucre.  Limb  of  the  adnate 
calyx  cup-shaped  and  entire  or  toothed,  or  forming  a  bristly  or 
plumose  pappus.  Corolla  tubular  ;  the  limb  four-  or  five-lobed, 
somewhat  irregular.  Stamens  four,  distinct,  or  rarely  united  in 
pairs,  often  unequal,  inserted  on  the  corolla.  Ovary  one-celled, 
one-ovuled.  Seed  suspended,  albuminous.  —  Ex.  Dipsacus,  the 
Teasel,  and  Scabiosa,  or  Scabious.  All  natives  of  the  Old  World. 
Some  are  cultivated  for  ornament.  Teasels  are  the  dried  heads  of 
Dipsacus  Fullonum,  covered  with  stiff  and  spiny  bracts,  with  re- 
curved points. 

FIG.  763.  Branch  of  Fedia  Fagopyrum.  764.  A  magnified  flower.  76.5.  A  fruit.  766.  An 
enlarged  cross-section  of  the  same,  and  the  cotyledons  of  the  seed  in  the  single  fertile  cell :  the 
two  empty  cells  are  confluent  into  one. 

FIG.  767.  Flower  of  a  Valerian,  with  one  of  the  pappus-like  bristles  of  the  calyx  unrolled. 
763.  Section  through  the  ovary  and  embryo;  the  bristles  of  the  calyx  broken  away. 


THE    MONOPETALOUS    ORDERS. 


433 


811.  Ord.  CompositSB  {the  Composite  or  Sunflower  Family).    Herbs 
or  shrubs ;    with  the  flowers  in  heads  (compound  flowers  of  the 

older  botanists),  crowded  on  a  receptacle, 
and  surrounded  by  a  set  of  bracts  (scales) 
forming  an  involucre  ;  the  separate  flowers 
often  furnished  with  bractlets  (chaff,  palece). 
Limb  of  the  adnate  calyx  obsolete,  or  a 
pappus  (305),  consisting  of  hairs,  bristles, 
scales,  &c.  Corolla  regular  or  irregular. 
Stamens  five,  as  many  as  the  lobes  or  teeth 
'^'  ^°  of  the  regular  corolla,  inserted  on  its  tube  : 

anthers  united  into  a  tube  (syngenesious.  Fig.  769).  Style  two- 
cleft.  Fruit  an  achenium,  with  a  single  erect  exalbuminous  seed, 
either  naked  or  crowned  with  a  pappus.  Embryo  straight.  —  This 
vast  but  very  natural  family  is  divided  into  three  sets  or  suborders  ; 
namely : 

812.  Subord.  TubuliflorEB.  Corolla  tubular  and  regularly  four-  or 
five-lobed,  either  in  all  the  flowers  (when  the  head  is  discoid) y  or  in 
the  central  ones  (those  of  the  disk)  only,  the  marginal  or  ray-flow- 
ers presenting  a  ligulate  or  strap-shaped  corolla.  —  Ex.  Liatris, 
Eupatorium,  &c. ;  where  the  heads  are  homogamous,  that  is,  the 
flowers  all  tubular,  similar,  and  perfect:  Helianthus  (Sunflower), 
Helenium,  Aster,  &c. ;  where  the  heads  are  heterogamous ;  the 
disk  flowers  being  tubular  and  perfect,  while  those  of  the  ray  are 
ligulate,  and  either  pistillate  only,  or  neutral  (473,  note),  that  is, 
destitute  of  both  stamens  and  pistils. 

813.  Subord.  LabiatiflorSE.  Corolla  of  the  disk-flowers  bilabiate. 
—  Ex.  Chaptalia,  of  the  United  States,  Mutisia,  Chsetanthera,  &c., 
of  South  America. 

814.  Subord.  Liguliflorae.  Corolla  of  all  the  flowers  (both  disk 
and  ray)  ligulate ;  all  perfect.  —  Ex.  The  Dandelion,  Lettuce, 
Cichory,  &c. 

815.  This  vast  family  comprises  about  a  tenth  part  of  all  Phse- 
nogamous  plants.  A  bitter  and  astringent  principle  pervades  the 
whole  order ;  which  in  some  is  tonic  (as  in  the  Camomile,  Anthe- 
mis  nobilis,  the  Boneset,  or  Thorough  wort,  Eupatorium  perfoliatum, 
&c.) ;  in  others  combined  with  mucilage,  so  that  they  are  demul- 
cent as  well  as  tonic  (as  in  Elecampane  and  Coltsfoot) ;  in  many, 
aromatic  and  extremely  bitter  (such  as  Wormwood  and  all  the  spe- 


FIG.  769.    Syngenesious  stamens  of  a  Composita.    770.  The  anthers  laid  open. 

37 


434 


EXOGENOUS    OR    DICOTYLEDONOUS   PLANTS. 


cies  of  Artemisia)  ;  sometimes  accompanied  by  acrid  qualities,  as 
in  the  Tansy  (Tanacetum  vulgare),  and  the  Mayweed  (Maruta 
Cotula),  the  bruised  fresh  herbage  of  which  blisters  the  skin.  The 
species  of  Liatris,  which  abound  in  terebinthine  juice,  are  among 
the  reputed  remedies  for  the  bites  of  serpents.  The  juice  of  Sil- 
phium  and  of  some  Sunflowers  is  resinous.  The  leaves  of  Soli- 
dago  odora,  which  owe  their  pleasant  anisate  fragrance  to  a  pe- 
culiar volatile  oil,  are  infused  as  a  substitute  for  tea.  From  the 
seeds  of  Sunflower,  and  several  other  plants  of  the  order,  a  bland 


771  772         773  780  781 

oil  is  expressed.     The  tubers  of  Helianthus  tuberosus  are  eaten 

FIG.  771.  Headof  Liatris  squarrosa  (discoid;  the  flowers  all  tubular  and  perfect).  772.  The 
same,  with  the  scales  of  one  side  of  the  imbricated  involucre  removed ;  and  also  all  the  flov/ers 
but  one,  showing  the  naked  flat  receptacle.  773.  Portion  of  one  of  the  plumose  bristles  of  the 
capillary  pappus.  774.  Head  of  Helenium  autumnale  (heterogamous)  ;  the  rays  neutral,  con- 
sisting merely  of  a  ligulate  corolla.  775.  The  same,  with  the  flowers  all  removed  from  the 
roundish  receptacle,  except  a  single  disk-flower  and  one  or  two  rays :  the  reflexed  scales  of  the 
involucre  in  a  single  series.  776.  Magnified  disk-flower  of  the  same;  the  corolla  exhibiting  the 
peculiar  venation  of  the  family;  namely,  the  veins  corresponding  to  the  sinuses,  and  sending  a 
branch  along  the  margins  of  the  lobes,  m.  The  same  with  the  corolla  removed ;  the  achenium 
crowned  with  the  limb  of  the  calyx  in  the  form  of  a  chaffy  pappus,  of  about  five  scales.  778.  A 
chaff  of  the  pappus  more  magnified.  779.  A  tubular  corolla  of  this  family  laid  open,  showing 
the  venation ;  and  also  the  five  syngenesious  anthers  united  in  a  tube,  through  which  the  two- 
cleft  style  passes.  780.  Head  of  Dracopis  amplexicaulis,  with  the  flowers  removed  from  the 
elongated  spike-like  receptacle,  except  a  few  at  the  base :  a,  achenium  of  one  of  the  disk-flow- 
ers, magnified,  partly  inclosed  by  its  bractlet  (chaff  or  palea)  ;  the  pappus  obsolete.  781.  Part 
of  the  involucre  and  alveolate  (honeycomb-like)  receptacle  of  Onopordon  or  Cotton-Thistle. 
782.  A  perfect  and  ligulate  flower  of  the  Dandelion,  with  its  hair-like  or  capillary  pappus. 


THE    MONOPETALOUS    ORDERS. 


435 


under  the  name  of  Jerusalem  artichokes.  True  artichokes  are  the 
fleshy  receptacle  of  Cynara  Scolymus.  The  flowers  of  Carthamus 
tinctorius,  often  called  Saffron,  yield  a  yellow  dye.  —  The  Liguli- 
florse,  or  Cichoracese,  all  have  a  milky  juice,  which  is  narcotic,  and 
has  been  employed  as  a  substitute  for  opium.  The  bland  young 
leaves  of  the  Garden  Lettuce  are  a  common  salad.  The  roasted 
roots  of  the  Wild  Succory  (Cichorium  Intybus)  are  extensively 
used  to  adulterate  coffee  :  and  the  roots  of  some  species  of  Trago- 
pogon  (Salsify,  Oyster-plant)  and  Scorzonera  are  well-known 
esculents. 

816.  Ord.  Lobeliaceae  [tlie  Lobelia  Family).  Herbs  or  somewhat 
shrubby  plants,  often  yielding  a  milky  juice,  with  alternate  leaves 
and  usually  showy  flowers.  Limb  of  the  adnate  calyx  five-cleft. 
Corolla  irregularly  five-lobed,  usually  appearing  bilabiate,  cleft  on 
one  side  nearly  or  quite  to  the  base.      Stamens  5,  epigynous,  co- 


herent into  a  tube.     Stigma  fringed.    Fruit  capsular,  two-  or  three- 


FIG.  783.  Campanula  rotundifolia,  much  reduced  in  size.  784.  Lobelia  inflata,  reduced  in 
size.  785.  A  flower  enlarged.  786.  The  united  filaments  and  anthers  inclosing  the  style ;  the 
coroUa  and  limb  of  the  calyx  cut  away.  787.  The  stigma  surrounded  by  a  fringe.  788.  Trans- 
verse section  of  a  capsule.    789,  Section  of  a  magnified  seed,  showing  the  embryo. 


436 


EXOGENOUS    OR   DICOTYLEDONOUS   PLANTS. 


(rarely  one-)  celled,  many-seeded.  Seeds  albuminous.  —  Ex.  Lo- 
belia. All  narcotico-acrid  poisons.  The  well-known  Lobelia  in- 
flata  (Indian  Tobacco)  is  one  of  the  most  powerful  articles  of  the 
materia  medica,  and  the  most  dangerous  in  the  hands  of  the  reck- 
less quacks  who  use  it.  Less  than  a  teaspoonful  of  the  seeds  or 
powdered  leaves  will  destroy  life  in  a  few  hours. 

817.  Ord.  CampannlaceSB  (tJie  Campanula  Family).  Herbs,  with 
a  milky  (slightly  acrid)  juice,  alternate  leaves,  and  usually  showy 
flowers.  Tube  of  the  calyx  adnate,  the  limb  commonly  five-cleft, 
persistent.  Corolla  regular,  campanulate,  usually  five-lobed,  with- 
ering. Stamens  five,  distinct.  Style  furnished  with  collecting 
hairs.  Capsule  two-  to  several-celled,  many-seeded.  Seeds  albu- 
minous.—  Ex.  Campanula  (Bell-flower,  Harebell).  Of  little  im- 
portance, except  for  ornament. 

818.  Ord.  Ericaceae  {the  Heath  Family).  Shrubs  or  sometimes 
herbs.  Flowers  regular  or  nearly  so,  4  -  5-merous,  the  petals 
sometimes  distinct.  Stamens  mostly  distinct,  free  from  the  co- 
rolla, as  many  or  twice  as  many  as  its  lobes,  and  inserted  with  it 
(either  hypogynous  or  epigynous),  anthers  two-celled,  often  ap- 
pendaged,  commonly  opening  by  terminal  pores.  Styles  and 
stigmas  united  into  one.  Ovary  with  two  or  more  cells  and  usually 
numerous  ovules,  free,  or  in  Vaccinese  coherent  with  the  calyx- 
tube.  Seeds  usually  indefinite,  albuminous.  —  Some  botanists  give 
the  rank  of  orders  to  the  following  suborders. 


819.  Subord.  Tacciniea;  {the  Whortleberry  Family).    Ovary  adnate 


FIG.  790.  Branch  of  Rhododendron  Lapponicum.  791.  Enlarged  flower,  with  its  pedicel 
and  bracts.  792.  Flower  with  the  corolla  removed,  more  enlarged.  793.  Capsule  of  R.  maxi- 
mum, opening  by  septicidal  dehiscence;  the  valves  breaking  away  from  the  persistent  axis,  or 
columella. 


THE    MONOPETALOUS    ORDEKS. 


437 


to  the  tube  of  the  calyx,  becoming  a  berry  or  a  drupe-like  fruit. 
Shrubs,  with  scattered  leaves,  often  evergreen.  —  Ex.  Vaccinium 
(Whortleberry),  Oxycoccus  (the  Cranberry). 

820.  Subord.  Ericineae  (the  proper  Heath  Family).  Ovary  free 
from  the  calyx.  Fruit  capsular,  sometimes  baccate  or  drupaceous. 
Testa  conformed  to  the  nucleus  of  the  seed.  Mostly  shrubs. 
Leaves  various,  often  evergreen.  Petals  rarely  almost  or  entirely 
distinct.  —  Ex.  Erica  (Heath),  Kalmia,  Rhododendron,  Gaulthe- 
ria,  Andromeda,  &c. 


821.  Snbord.  Pyrolese  (the  Pyrola  Family).    Ovary  free  from  the 
calyx.     Petals  distinct  or  nearly  so.     Fruit  a  capsule.     Seeds  with 


FIG.  794.  Gaultheria  procumbens  (Wintergreen,  &c.).  795.  The  enlarging  calyx  in  the  im- 
mature fruit.  796.  Vertical  section  of  the  pulpy  or  berry -like  calyx  and  the  included  capsule 
(the  seeds  removed  from  the  placenta  in  one  cell),  797.  Horizontal  section  of  the  same,  show- 
ing the  five-celled  capsule,  with  a  placenta  proceeding  from  the  inner  angle  of  each  cell.  798. 
Section  of  a  seed,  magnified.  799.  Flower  of  a  Vaccinium  (Whortleberry).  800.  Vertical  sec- 
tion of  the  ovary  and  adherent  calyx.  801.  Anther  of  Vaccinium  Vitis-Idaea;  each  cell  pro- 
longed into  a  tube,  and  opening  by  a  terminal  pore.  802.  Anther  of  Vaccinium  Myrtillus ;  the 
connectivum  furnished  with  two  appendages.  803.  Stamen  of  an  Andromeda  (Cassiope),  show- 
ing the  appendages  of  the  connectivum.  804.  Stamen  of  Arctostaphylos  UvaUrsi,  showing  the 
separate  anther-cells,  opening  by  a  terminal  pore,  the  appendages  of  the  connectivum,  and  the 
filament,  which  is  swollen  at  the  base, 

37* 


438 


EXOGENOTTS    OR   DICOTYLEDONOUS   PLANTS. 


a  loose  cellular  testa,  not  conformed  to  the  nucleus.    Mostly  herbs. 
Leaves  flat  and  broad.  —  Ex.  Pyrola,  Chimaphila,  Galax. 

822.  Subord.  Monotropeae  {the  Indian-Pipe  Family).  Ovary  free 
from  the  calyx.  Petals  distinct  or  united.  Anthers  opening  lon- 
gitudinally or  by  transverse  chinks.  Fruit  a  capsule.  Seeds  with 
a  loose  or  winged  testa.  Parasitic  herbs,  destitute  of  green  color, 
and  with  scales  instead  of  leaves.  —  Ex.  Monotropa,  the  Indian 
Pipe.  —  In  this  widely  diffused  order  the  bark  and  foliage  are  gen- 
erally astringent,  often  stimulant  or  aromatic  from  a  volatile  oil  or 
a  resinous  matter,  and  not  seldom  narcotic.  Thus,  the  leaves  of 
Rhododendron,  Kalmia,  and  all  the  related  plants,  are  deleterious 
(being  stimulant  narcotics),  or  suspicious.  The  honey  made  from 
their  flowers  is  sometimes  poisonous.     The  Uva-Ursi  and  the  Chi- 


maphila (Pipsissewa)  are  the  chief  medicinal  plants  of  the  order. 


FIG.  805.  Pyrola  cbloranlha,  reduced  in  size.  806.  Enlarged  flower.  807.  Magnified  sta- 
men. 808.  Pistil.  809.  Cross-section  of  the  capsule.  810.  A  highly  magnified  seed.  811.  The 
nucleus  removed  from  the  loose  cellular  testa,  and  divided,  showing  the  very  minute  embryo. 

FIG.  812.  Monotropa  uniflora.  813.  A  petaL  814.  Capsule,  with  the  stamens.  815.  Trans- 
verse section  of  the  same ;  the  thick  and  lobed  placenta  covered  with  very  minute  seeds. 


THE    M0N0PETAL0T7S    OEDERS.  439 

The  berries  are   generally  edible  (Whortleberries,  Wintergreen, 
&c.).     Many  are  very  ornamental  plants. 

823.  Ord.  EpacridaeeaB,  which  takes  the  place  of  Heaths  in  Aus- 
tralia, essentially  differs  from  them  only  in  the  one-celled  anthers. 

824.  Ord.  AquifoIiaceSB  {the  Holly  Family).  Trees  or  shrubs, 
commonly  with  coriaceous  leaves,  and  small  axillary  flowers.  Ca- 
lyx of  four  to  six  sepals.  Corolla  four-  to  six-parted  or  cleft :  the 
stamens  as  many  as  its  segments  and  alternate  with  them,  inserted 
on  the  base  of  the  corolla.  Anthers  opening  longitudinally.  Ovary 
two-  to  six-celled  ;  the  cells  with  a  single  suspended  ovule.  Fruit 
drupaceous,  with  two  to  six  stones  or  nucules.  Embryo  minute, 
in  hard  albumen.  —  Ex.  Dex  (the  Holly)  and  Prinos.  The  bark 
and  leaves  contain  a  tonic,  bitter,  extractive  matter.  The  leaves 
of  a  species  of  Ilex  are  used  for  tea  in  Paraguay  :  and  the  famous 
hlack  drink  of  the  Creek  Indians  is  prepared  from  the  leaves  of 
Ilex  vomitoria  (Cassena) ;  which  are  still  used  as  a  substitute  for 
tea  in  some  parts  of  the  Southern  States. 

825.  Ord.  EbcnaceaB  (the  Ebony  Family).  Trees  or  shrubs,  des- 
titute of  milky  juice,  with  alternate,  mostly  entire  leaves,  and 
polygamous  flowers.  Calyx  three-  to  six-cleft,  free  from  the  ova- 
ry. Corolla  three-  to  six-cleft,  often  pubescent  Stamens  twice 
to  four  times  as  many  as  the  lobes  of  the  corolla,  inserted  on 
them.  Ovary  three-  to  several-celled  ;  the  style  with  as  many 
divisions.      Fruit  a  kind  of  berry,  with   large   and  bony  seeds. 


Embryo  shorter  than   the  hard   albumen.  —  Ex.    Diospyros,  the 

FIG.  816.  Perfect  flower  of  Diospjrros  Yirginiana,  the  Persimmon.  S17.  Tba  corcdia,  laid 
open,  and  stamens.  818.  The  fruit.  819.  Section  through  the  fruit  and  boDy  seeds.  820.  Ver- 
tical section  of  a  seed.    821.  The  detached  emtnya 


440  EXOGENOUS    OR   DICOTTLEDONOTTS   PLANTS. 

Persimmon.  The  fruit,  which  is  extremely  austere  and  astrin- 
gent when  green,  is  sweet  and  eatable  when  fully  ripe.  The  bark 
is  powerfully  astringent.  Ebony  is  the  wood  of  D.  Ebenus  and 
other  African  and  Asiatic  species. 

826.  Ord.  StyracaceSB  (the  Storax  Family).  Shrubs  or  trees  with 
perfect  flowers.  Calyx-tube  coherent  either  with  the  base  of  the 
ovary,  or  with  its  whole  surface.  Styles  and  stigmas  perfectly 
united  into  one.  Stamens  more  or  less  united.  Cells  of  the  ovary 
opposite  the  calyx-lobes.  Otherwise  much  as  in  the  last  family. — 
Ex.  Styrax,  Halesia,  Symplocos.  Some  yield  a  fragrant,  bal- 
samic resinous  substance  ;  such  as  Storax  and  Benzoin,  containing 
Benzoic  acid.  The  sweet  leaves  of  our  Symplocos  tinctoria  afford 
a  yellow  dye. 

827.  Ord.  Sapotaceae  {the  SapodlUa  Family).  Trees  or  shrubs, 
usually  with  a  milky  juice  ;  the  leaves  alternate,  entire,  coriaceous, 
the  upper  surface  commonly  shining.  Flowers  perfect,  regular,  ax- 
illary, usually  in  clusters.  Calyx  four-  to  eight-parted.  Corolla  four- 
to  eight-  (or  many-)  cleft.  Stamens  distinct,  inserted  on  the  tube 
of  the  corolla,  commonly  twice  as  many  as  its  lobes,  half  of  them 
fertile  and  opposite  the  lobes,  the  others  petaloid  scales  or  filaments 
and  alternate  with  them  :  anthers  extrorse.  Ovary  4  -  12-celled, 
with  a  single  ovule  in  each  cell.  Styles  united  into  one.  Fruit  a 
berry.  Seeds  with  a  bony  testa,  with  or  without  albumen.  —  Ex. 
Bumelia  of  the  Southern  United  States.  The  fruit  of  many  spe- 
cies is  sweet  and  eatable  ;  such  as  the  Sapodilla  Plum,  the  Marma- 
lade, the  Star-Apple,  and  other  West  Indian  species.  The  large 
seeds,  particularly  of  some  kinds  of  Bassia,  yield  a  bland  fixed  oil, 
which  is  sometimes  thick  and  like  butter,  as  in  the  Chee  of  India 
(B.  butyracea),  and  the  African  Butter-tree,  or  Shea,  described  by 
Mungo  Park. 

828.  Ord.  MjTSinaceSB.  Trees  or  shrubs,  mostly  with  alternate 
coriaceous  leaves,  which  are  often  dotted  with  glands,  and  with  all 
the  characters  of  Primulaceee,  except  the  drupaceous  fruit  and 
arborescent  habit.  — Nearly  all  tropical  (Ardisia,  Myrsine). 

829.  Ord.  PrimulaceSB.  Herbs,  with  opposite,  whorled,  or  alter- 
nate leaves,  often  with  naked  scapes  and  the  leaves  crowded  at  the 
base.  Calyx  four-  or  five-cleft  or  toothed,  usually  persistent. 
Corolla  rotate,  hypocrateriform,  or  campanulate.  Stamens  insert- 
ed on  the  tube  of  the  corolla,  as  many  as  its  lobes  and  opposite 
them!      Ovary  free,   one-celled   with  a  free   central   placenta! 


THE    MONOPETALOUS    ORDERS. 


441 


Ovules  mostly  indefinite  and  amphitropous.  Style  and  stigma  sin- 
gle. Fruit  capsular  :  the  fleshy  central  placenta  attached  to  the 
base  of  the  cell.  Seeds  albuminous.  Embryo  transverse.  —  Ex. 
Primula  (Primrose),  Cyclamen,  Anagallis.  In  Samolus,  the  ca- 
lyx coheres  with  the  base  of  the  ovary,  and  there  is  a  row  of  sterile 
filaments  occupying  the  normal  position  of  the  first  set  of  stamens, 
namely,  alternate  with  the  lobes  of  the  corolla.  Of  little  conse- 
quence, except  for  their  beauty. 


830.  Ord.  PlantaginaceSB  {the  Plantain  Family).  Chiefly  low 
herbs,  with  small  spiked  flowers  on  scapes,  and  ribbed  radical 
leaves.  —  Calyx  four-cleft,  persistent.  Corolla  tubular  or  urn- 
shaped,  scarious  and  persistent ;  the  limb  four-cleft.  Stamens 
four,  inserted  on  the  tube  of  the   corolla  alternate  with  its  seg- 

FIG.  822.  Primula  pusilla.  823.  The  corolla  removed ;  its  tube  laid  open.  824.  The  calyx 
divided  vertically,  showing  the  pistil.  825.  Vertical  section  of  the  ovary  and  of  the  free  central 
placenta,  covered  with  ovules,  which  nearly  fills  the  cell.  826.  Capsule  of  Primula  veris,  de- 
hiscent at  the  summit  by  numerous  teeth.  827.  A  magnified  seed.  828.  Section  of  the  same, 
exhibiting  the  transverse  embryo. 

FIG.  829.  Branch  of  Anagallis  arvensis  (Pimpernel),  with  a  capsule  showing  the  line  of  cir- 
cumscissile  dehiscence.    830.  The  capsule  (pyxis,  616),  with  the  lid  falling  away. 


442 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


ments;    the  persistent  filaments  long  and  flaccid.      Ovary  two- 
834  833  celled  :    style   single.     Capsule   (pyxis) 

membranaceous,  opening  by  circumscis- 
sile  dehiscence  ;  the  cells  one-  to  several- 
seeded.  Embryo  large,  straight,  in 
fleshy  albumen.  —  Ex.  Plantago,  the 
Plantain,  or  Ribgrass,  is  the  principal 
genus  of  the  order.  It  is  destitute  of 
any  important  economical  qualities. 
831.  Ord.  Plumbaginaceae  (the  Leadwort 

Family).  Perennial  herbs,  or  somewhat 
shrubby  plants ;  with  the  flowers  often 
on  simple  or  branching  scapes  ;  and  the 
leaves  crowded  at  the  base,  entire, 
mostly  sheathing  or  clasping.  —  Calyx 
tubular,  plaited,  five-toothed,  persistent. 
Corolla  hypocrateriform,  with  a  five- 
parted  limb,  the  five  stamens  inserted  on 
the  receptacle  opposite  its  lobes  (Plumbago) ;  or  else  of  five  almost 
distinct  unguiculate  (scarious  or  coria- 
ceous) petals,  with  the  stamens  inserted 
on  their  claws !  (Statice,  &c.)  In  the  for- 
mer case  the  five  styles  are  united  nearly 
to  the  top  ;  but  in  the  latter  they  are  sep- 
arate !  Ovary  one-celled,  with  a  single 
ovule  pendulous  from  a  strap-shaped  fu- 
niculus which  rises  from  the  base  of  the 
cell.  Fruit  a  utricle,  or  opening  by 
five  valves.  Embryo  large,  in  thin  albu- 
men.—  Ex.  Statice  (Marsh  Rosemary, 
Sea  Lavender),  and  Armeria  (Thrift) ; 
sea-side  or  saline  plants.  The  Statices 
have  astringent  roots ;  none  more  so 
than  those  of  our  own  Marsh  Rosemary 
or  Sea  Lavender  (S.  Caroliniana),  one  ^° 

of  the  best  and  most  intense  astringents  of  the  materia  medica. 


FIG.  831.  A  flower  enlarged.  832.  Pistil.  833.  Capsule  (pyxis,  616)  with  the  marcescent 
corolla.    834.  Cross-sectionof  the  capsule  and  seeds,    835.  Vertical  section  of  a  seed. 

FIG.  836.  Corolla,  and  837,  calyx  of  Thrift  (Armeria  vulgaris).  838.  Pistil  with  distinct 
styles.  839.  Cross-section  of  the  pod  and  seed.  840.  Vertical  section  of  the  ovary,  magnified, 
to  show  the  ovule. 


THE    MONOPETALOUS    ORDERS. 


443 


832.  Ord.  Lentibulacese  (the  Bladderwort  Family).  Herbs,  grow- 
ing in  water,  or  wet  places,  with  the  flowers  on  scapes ;  the  leaves 
either  submersed  and  dissected  into  filiform  segments  resembling 
rootlets,  and  commonly  furnished  with  air-bladders  to  render  them 
buoyant ;  or,  when  produced  in  the  air,  entire  and  som'ewhat 
fleshy,  clustered  at  the  base  of  the  scape.  Flowers  showy,  very 
irregular.  Calyx  of  two  sepals,  or  unequally  five-parted.  Corolla 
bilabiate,  personate ;  the  very  short  tube  spurred.  Stamens  two, 
inserted  on  the  upper  lip  of  the  corolla :  anthers  one-celled.  Ovary 
free,  one-celled,  with  a  free  central  placenta !  bearing  numerous 
ovules.  Fruit  a  capsule.  Seeds  destitute  of  albumen.  Embryo 
straight.  —  Ex.  Utricularia  (Bladderwort),  Pinguicula.  Unimpor- 
tant plants. 

833.  Ord.  OrobanchaceSB  {the  Broom-Rape  Family).     Herbs,  des- 


titue  of  green  foliage,  and  with  scales  in  place  of  leaves,  parasitic 


FIG.  841.  Branch  of  Epiphegua  Virginiana  (Beech-drops),  nearly  of  the  natural  size:  the 
lower  flowera,  with  short  imperfect  corollas,  alone  producing  ripe  seeds.  842.  A  flower  en- 
larged. 843.  Longitudinal  section  of  the  same.  844.  Longitudinal  section  of  the  ovary,  more 
magnified,  showing  one  of  the  parietal  placentae  covered  with  minute  ovules.  845.  Cross-sec- 
tion of  the  same,  showing  the  two  parietal  placentas.  846.  A  highly  magnified  seed.  847.  Sec- 
tion of  the  same,  exhibiting  the  minute  embryo  next  the  hilum. 

FIG.  848.  Orobanche  uniliora,  reduced  in  size.  849.  A  flower  about  the  size  of  nature. 
850.  The  same  laid  open,  showing  the  didynamous  stamens  and  the  pistil.  861.  A  magnified 
anther.    852.  A  magnified  seed.    853.  Section  of  the  same. 


444  EXOGENOUS    OR   DICOTYLEDONOUS   PLANTS. 

on  the  roots  of  other  plants  ;  the  flowers  solitary  or  spicate.  Calyx 
persistent,  four-  or  five-toothed  or  bilabiate.  Corolla  withering  or 
persistent,  with  a  bilabiate  or  more  or  less  irregular  limb.  Sta- 
mens four,  didynamous,  inserted  on  the  corolla.  Ovary  free,  one- 
celled,  with  two  parietal  placentae  !  which  are  often  two-lobed,  or 
divided.  Capsule  inclosed  in  the  persistent  corolla.  Seeds  very 
numerous,  minute.  Embryo  minute  at  the  extremity  of  the  albu- 
men.—  Ex.  Orobanche,  Epiphegus  (Beech-drops),  &;c.  Astrin- 
gent, bitter,  and  escharotic.  The  pulverized  root  of  Epiphegus 
(thence  called  Cancer-root)  is  applied  to  open  Cancers.* 

834.  Ord.  BignoniaceSB  (the  Bignonia  Family).  Mostly  trees,  or 
climbing  or  twining  shrubby  plants,  with  large  and  showy  flowers, 
and  opposite,  simple,  or  mostly  pinnately-compound  leaves.  Ca- 
lyx five-parted,  two-parted,  or  bilabiate,  often  spathaceous.  Corol- 
la with  an  ample  throat,  and  a  more  or  less  irregular  five-lobed  or 
bilabiate  limb.  Stamens  five,  inserted  on  the  corolla,  of  which 
one,  and  often  three,  are  reduced  to  sterile  filaments  or  rudiments : 
when  four  are  fertile,  they  are  didynamous.  Ovary  two-celled, 
with  the  placentae  in  the  axis ;  the  base  surrounded  by  a  fleshy 
ring  or  disk.  Capsule  woody  or  coriaceous,  pod-shaped,  two- 
valved,  many-seeded.  Seeds  winged,  destitute  of  albumen.  Co- 
tyledons foliaceous,  flat,  heart-shaped,  also  notched  at  the  apex. 
—  Ex.  Bignonia  (Trumpet-Creeper),  Catalpa,  and  other  tropical 
genera.     Of  little  importance,  except  as  ornamental  plaijts. 

835.  Subord.  Sesameac  {the  Sesamum  Family)  has  few  and  wingless 
seeds  ;  the  fruit  indurated  or  drupaceous,  often  two-  to  four-horned, 
sometimes  perforated  in  the  centre  from  the  dissepiments  not 
reaching  the  axis  before  they  diverge  and  become  placentiferous, 
and  spuriously  four-  to  eight-celled  by  the  various  cohesion  of 
parts  of  the  placentae  with  the  walls  of  the  pericarp.  —  Ex.  Sesa- 
mum, Martynia  (Unicorn-plant),  and  some  other  tropical  plants. 

836.  Ord.  AcanthaceBB  (the  Acanthus  Family).  Herbs  or  shrubby 
plants,  with  bracteate,  often  showy  flowers,  and  opposite,  simple 
leaves,  without  stipules.  Calyx  of  five  sepals  united  at  the  base, 
or  combined  into  a  tube,  persistent.     Corolla  bilabiate,  or  some- 


*  Ord.  GESNERIACE^,  consisting  of  tropical  herbs,  with  green  foliage 
and  showy  flowers,  the  calyx  often  partly  adherent  to  the  ovary,  agrees  with 
drobanchacese  in  the  parietal  placentation,  by  which  both  are  distinguished 
frora  all  other  orders  of  this  group. 


THE    MONOPETALOUS    ORDERS. 


445 


times  nearly  equally  five-lobed :  gestivation  convolute !  Stamens 
four  and  didynamous,  or  only  two,  the  anterior  pair  being  abortive 
or  obsolete,  inserted  on  the  corolla.  Ovary  two-celled,  with  the 
placentae  in  the  axis,  often  few-ovuled.  Seeds  (sometimes  only 
one  or  two  in  each  cell)  usually  supported  by  hooked  processes  of 
the  placenta,  destitute  of  albumen.  —  Ex.  Acanthus,  Dianthera. 
A  large  family  in  the  tropics.     Many  are  ornamental. 

837.  Ord.  Scroplmlariacem  {the  Figwort  Family).  Herbs,  or 
sometimes  shrubby  plants ;  with  opposite,  verticillate,  or  alternate 
leaves.  Calyx  of  four  or  five  more  or  less  united  sepals,  persist- 
ent. Corolla  bilabiate,  personate,  or  more  or  less  irregular;  the 
lobes  imbricated  in  aestivation.  Stamens  four  and  didynamous,  the 
fifth  stamen  sometimes  appearing  in  the  form  of  a  sterile  filament^ 


or  very  rarely  antheriferous ;  or  often  only  two,  one  pair  being; 
38 


446 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


either  suppressed  or  reduced  to  sterile  filaments,  inserted  on  the 
corolla.  Ovary  free,  two-celled,  with  the  placentae  united  in  the 
axis.  Capsule  two-valved.  Seeds  indefinite,  albuminous.  Em- 
bryo small.  —  Ex.  Scrophularia,  Verbascum  (Mullein,  which  is 
remarkable  for  the  nearly  regular  corolla,  with  five  perfect  sta- 
mens), Linaria,  Antirrhinum  (Snapdragon),  &c.  —  The  plants 
of  this  large  and  important  order  are  generally  to  be  suspected  of 
deleterious  (bitter,  acrid,  or  drastic)  properties.  The  most  impor- 
tant medicinal  plant  is  the  Foxglove  (Digitalis  purpurea),  so  re- 
markable for  its  power  of  lowering  the  pulse.  Numerous  species 
are  cultivated  for  ornament. 

838.  Ord.  YcrbenaceSB  (the  Vervain  Family).  Herbs,  shrubs,  or 
even  trees  in  the  tropics,  mostly  with  opposite  leaves.  Calyx 
tubular,  four-  or  five-toothed,  persistent.  Corolla  bilabiate,  or  the 
four-  or  five-lobed  limb  more  or  less  irregular.  Stamens  mostly 
four  and  didynamous,  occasionally  only  two,  inserted  on  the  co- 
rolla. Ovary  free,  entire,  two-  to  four-celled.  Fruit  drupaceous, 
baccate,  or  dry,  and  splitting  into  two  to  four  indehiscent  one- 
seeded  portions.  Seeds  with  little  or  no  albumen.  Embryo 
straight,  inferior.  — Ex.  Verbena  (Vervain,  Fig.  863-871)  is  the 


principal  representative  in  cooler  regions.     There  are  many  others 

FIG.  863  and  864.  Flower  of  a  Verbena  enlarged,  865,  The  corolla  laid  open,  866.  Pistil. 
867.  The  fruit.  868.  Crosssectionof  the  young  fruit  and  the  contained  seeds.  869.  Fruit  sep- 
arating into  its  four  nucules.  870.  Cross-section  of  one  nucule  or  pericarp,  and  a  vertical  sec- 
tion of  the  lower  part,  showing  the  surface  of  the  contained  seed.  871.  Vertical  section  through 
ihi  nucule,  seed,  and  embryo,  _ 


THE    MONOPETALOUS    ORDERS. 


447 


in  the  tropics,  mostly  trees ;  one  of  which  is  the  gigantic  Indian 
Teak  (Tectona  grandis),  remarkable  for  its  very  heavy  and  dura- 
ble wood,  which  abounds  in  silex.  The  leaves  of  the  Aloysia 
citriodora  of  the  gardens  yield  an  agreeable  perfume.  Others 
are  bitter  and  aromatic. 

839.  Snbord.  ?  Phrymacese  (Phryma)  is  separated  on  account  of 
its  simple  pistil,  uniovulate  ovary,  spirally  convolute  cotyledons, 
and  superior  radicle. 

840.  Ord.  LabiatSB  {the  Labiate  or  Mint  Family).  Herbs,  or 
somewhat  shrubby  plants,  with  quadrangular  stems,  and  opposite 
or  sometimes  whorled  leaves,  replete  with  receptacles  of  volatile 
oil.  Flowers  in  axillary  or  terminal  cy mules  (412),  rarely 
solitary.  Calyx  tubular,  persistent,  five-toothed  or  cleft,  or  bi- 
labiate. Corolla  bilabiate.  Stamens  inserted  on  the  corolla, 
four,  didynamous,  or  only  two,  one  of  the  pairs  being  abortive 
or  wanting.  Ovary  free,  deeply  four-lobed  ;  the  central  style 
proceeding  from  the  base  of  the  lobes.  Fruit  consisting  of  four 
(or  fewer)  little  nuts  or  achenia,  included  in  the  persistent  calyx. 
Seeds  with  little  or  no  albumen.  —  Ex»   The  Sage,  Rosemary, 


Lavender,  Thyme,  Mint,  &c.,  are  familiar  representatives  of  this 


FIG.  872.  Flower  of  Glechoma  hederacea,  or  Ground  Ivy.  873.  Approximate  anthers  of  one 
pair  of  stamens,  magnified.  874.  Flower  of  aLamiiim.  875.  Corolla  of  L.  amplexicaule  (Dead 
Nettle)  laid  open,  showing  the  didynamous  stamens,  &c.  876.  Calyx  and  corolla  of  Scutellaria 
galericuiata  (Skull-cap).  877.  Section  of  the  enlarged  calyx  of  the  same,  bringing  to  view  the 
deeply  four-lobed  ovary,  raised  on  a  short  gynobase.  878.  Cross-section  of  a  magnified  ache- 
nium.  879.  Vertical  section  of  the  same,  showing  the  embryo.  881.  Flower  of  Teucrium 
Canadense.  882.  Magnified  anther  of  the  same.  883.  Stamen  of  the  Thyme.  884.  Flower  of 
Monarda.  885.  Magnified  anther  of  the  same.  886.  Flower  of  a  Salvia;  the  calyx  as  well 
as  the  corolla  bilabiate.  880.  Magnified  stamen  of  the  same,  with  widely  separated  anther- 
cells  one  of  which  (a)  ia  polliniferous,  the  other  {b)  imperfect. 


448 


EXOGENOtrS    OR   DICOTYLEDONOUS    PLANTS. 


universally  recognized  order.  Their  well-known  cordial,  aro- 
matic, and  stomachic  qualities  depend  upon  a  volatile  oil,  con- 
tained in  glandular  receptacles  which  abound  in  the  leaves  and 
other  herbaceous  parts,  with  which  a  bitter  principle  is  variously- 
mixed.     None  are  deleterious. 

841.  Ord.  BoraginacefiB  (the  Borage  Family).  Herbs,  or  some- 
times shrubby  plants ;  with  round  stems,  and  alternate,  rough 
leaves ;  the  flowers  often  in  one-sided  clusters  (406),  which  are 
spiral  before  expansion.  Calyx  of  five  leafy  and  persistent  sepals, 
more  or  less  united  at  the  base,  regular.  Corolla  regular ;  the 
limb  five-lobed,  often  with  a  row  of  scales  in  the  throat.  Stamens 
inserted  on  the  corolla,  as  many  as  its  lobes  and  alternate  with 
them.  Ovary  deeply  four-lobed,  the  style  proceeding  from  the 
base  of  the  lobes,  which  in  fruit  become  little  nuts  or  hard  achenia. 
Seeds  with  little  or  no  albumen.  —  Ex.  Borago  (Borage),  Litho- 
spermum,  Myosotis,  Cynoglossum  (Hound's-tongue),  Heliotropium, 
&c.  In  Echium,  the  limb  of  the  corolla  is  somewhat  irregular, 
and  the  stamens  unequal.     Innocent  mucilaginous  plants,  with  a 


slight  astringency :  hence  demulcent  and  pectoral ;  as  the  roots  of 


FIG.  8S7.  Myosolis,  or  Forget-me-not.  83S.  The  rotate  corolla  laid  open,  showing  the 
scales  of  the  throat,  and  the  short  stamens.  889.  The  pistil,  with  its  fourlobed  ovary.  890, 
The  calyx  in  fruit ;  two  of  the  little  nuts  having  fallen  away  from  the  receptacle.  891.  Section 
of  a  nut,  or  rather  achenium,  showing  the  embryo.  S92.  Raceme  of  Symphytum  officinale 
(Comfrey).  893.  A  corolla  laid  open ;  exhibiting  the  lanceolate  and  pointed  scales  of  the  throat, 
alternate  with  the  stamens. 


THE    MONOPETALOUS    ORDERS. 


449 


the  Comfrey.  The  roots  of  Anchusa  tinctoria  (Alkanet)  and  Bat- 
schia  canescens  (used  by  the  aborigines  under  the  name  of  Puc- 
coon)  yield  a  red  dye. 

842.  Ord.  nydrophyllaceSB  (the  Water-leaf  Family).  Herbs,  usu- 
ally with  alternate  and  lobed  or  pinnatifid  leaves  ;  the  flowers 
mostly  in  cymose  clusters  or  unilateral  racemes.  Calyx  five-cleft, 
with  the  sinuses  often  appendaged,  persistent.  Corolla  regular, 
imbricated  or  convolute  in  aestivation,  usually  furnished  with  scales 
or  honey-bearing  grooves  inside  ;  the  five  stamens  inserted  into  its 
base,  alternate  with  the  lobes.  Ovary  free,  with  two  parietal  pla- 
centae, which  sometimes  dilate  in  the  cell  and  appear  like  a  kind 
of  inner  pericarp  in  the  capsular  fruit.  Styles  partly  united. 
Seeds  few,  crustaceous.  Embryo  small,  in  hard  albumen.  —  Ex. 
Hydrophyllum,  Nemophila,  and  Phacelia ;  nearly  all  North  Amer- 
ican plants,  some  of  them  handsome  in  cultivation. 


FIG.  894.  Hydrophyllum  Virginicum.  895.  A  flower,  nearly  of  the  natural  Size.  896.  Co- 
rolla laid  open.  897.  Capsule,  with  the  persistent  calyx  and  style.  898.  Cross-section  of  the 
same,  the  cavity  filled  by  two  seeds.  899.  Magnified  seed.  900.  Section  of  the  same.  901. 
Highly  magnified  embryo. 

38* 


450 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


843.  Ord.  HydroleaceSB  differs  (not  sufficiently)  fronn  the  last  by 
the  simple  and  entire  leaves,  the  two-celled  ovary,  the  two  distinct 
styles,  and  the  numerous  seeds.  —  Ex.  Hydrolea,  Nama  :  chiefly 
natives  of  warm  regions. 

844.  Ord.  PolemoniaceaB  {the  Polemonium  Family).  Herbs,  with 
alternate  or  opposite  leaves,  and  panicled,  corymbose,  or  clustered 
flowers.  Calyx  five-cleft.  Corolla  regular,  with  a  five-lobed  limb, 
convolute  in  aestivation.  Stamens  five,  inserted  on  the  corolla 
alternate  with  its  lobes,  often  unequal.  Ovary  free,  three-celled, 
with  a  thick  axis,  bearing  few  or  numerous  ovules :  styles  united 
into  one :  stigmas  three.  Capsule  three-valved,  loculicidal ;  the 
valves  also  usually  breaking  away  from  a  thick  central  column 
which  bears  the  seeds.  Embryo  straight,  in  fleshy  or  horny  albu- 
men. —  Ex.  Polemonium  (Greek  Valerian),  Phlox,  Gilia.  Chiefly 
North  American ;  many  are  very  common  ornamental  plants  in 
cultivation. 


845.  Ord.  Diapensiaceae,  Low,  prostrate,  and  tufted  suffruticose 
plants  ;  with  crowded  and  evergreen  heath-like  leaves,  and  solitary 
terminal  flowers.  Differing  from  the  last  family  chiefly  in  tli« 
transversely  two-valved  anthers,  and  amphitropous  seeds.     Con- 


FIG.  902.  Flowers  of  Polemonium.  903.  Flowers  of  Phlox.  90i.  Corolla  of  the  same  laid 
open,  showing  the  stamens  unequally  inserted  on  its  tube,  905.  Pistil  of  the  same.  906.  Cross- 
section  of  the  capsule  of  Polemonium.  907.  Cross-section  of  a  magnified  seed.  911.  Perpen- 
dicular section  of  the  same.  912.  Magnified  embryo.  908.  Cross-section  of  the  dehiscent  cap- 
sule of  Collomia.    909,910.  Capsule  of  Leptodacty  Ion. 


THE    MONOPETALOUS    ORDERS. 


451 


sists  of  two  plants  only,  viz.  the  Alpine  Diapensia,  and  Pyxidan- 
thera,  of  the  Pine-barrens  of  New  Jersey,  &c. 


846.  Ord.  ConvolvulaceSB  {the  Convolvulus  Family).  Twining  or 
trailing  herbs  or  shrubs,  often  with  milky  juice ;  the  leaves  alter- 
nate, and  the  flowers  regular.  Calyx  of  five  sepals,  imbricated,  or 
usually  more  or  less  united,  persistent.  Corolla  supervolute  in 
aestivation  (Fig.  363) ;  the  limb  often  entire.  Stamens  five,  insert- 
ed on  the  tube  of  the  corolla  near  the  base.  Ovary  free,  two-  to 
four-celled,  with  one  or  two  erect  ovules  in  each  cell :  styles 
united,  or  more  or  less  distinct.  Capsule  two-  to  four-  (or  by  oblit- 
eration one-)  celled ;  the  valves  falling  away  from  the  persistent 
dissepiments  (septifragal).  Seeds  large,  with  a  little  mucilaginous 
albumen  :  embryo  curved,  and  the  foliaceous  cotyledons  usually 
crumpled.  —  Ex.  Convolvulus  (Morning-Glory,  Bindweed).  They 
all  contain  a  peculiar  strongly  purgative  resinous  matter,  which  is 
chiefly  found  in  the  acrid,  milky  juice  of  their  thickened  or  tuber- 
ous roots.  Convolvulus  Jalapa,  and  other  Mexican  species,  fur- 
nish the  Jalap  of  the  shops.  The  more  drastic  Scammony  is  de- 
rived from  the  roots  of  C.  Scammonia  of  the  Levant.  There  is 
much  less  of  this  in  those  of  Convolvulus  panduratus  (Mechameck^ 
Man-of-the-Earth,  Wild  Potato-vine) :  while  those  of  C.  macrorhi- 
^us  of  the  Southern  States,  which  sometimes  weigh  40  or  50  pounds, 
are  farinaceous,  with  so  slight  an  admixture  of  the  peculiar  resin 

FIG.  913.  Pyxidanlhera  barbulata,  natural  size.  914.  Pistil,  in  fruit,  and  the  persistent 
calyx,  enlarged.  915.  Corolla  and  stamens.  916.  Same  laid  open.  917.  A  separate  stamen 
magnified.    918.  Section  of  the  dehiscent  capsule.    919.  A  seed. 


452 


EXOGENOUS    OR   DICOTYLEDONOUS   PLANTS. 


as  to  be  quite  inert ;  as  is  also  the  case  with  the  Batatas,  or  Sweet 
Potato,  an  important  article  of  food.  —  To  this  family  are  appended 


847.  Subord.  DichondreSB.      Ovaries  two  to  four,  either  entirely 
distinct  or  with   their  basilar  styles  united  in  pairs.      Creeping 


FIG.  921.  Convolvulus  purpureus.  922.  The  pistil.  923.  Section  of  the  capsule,  and  of  the 
two  seeds  in  each  cell.  924.  Capsule  (reduced  in  size),  when  the  valves  have  fallen  away  from 
the  dissepiments ;  and  one  of  the  seeds.  925.  Magnified  cross-section  of  a  seed.  926.  Embryo, 
with  the  leaf-like  two-lobed  cotyledons  spread  out.  927.  Same,  with  the  two  cotyledons  sepa- 
rated and  laid  open. 

FIG.  923.  A  piece  of  Cuscuta  Gronovii,  the  common  Dodder  of  the  Northern  United  States, 
of  the  natural  size.  929.  A  flower  enlarged.  930.  The  same  laid  open.  931.  Section  of  the 
ovary.  932.  Section  of  the  capsule  and  seeds.  933,  The  spiral  embryo  detached.  934.  The 
same  in  germination. 


THE    MONOPETALOUS    ORDERS. 


453 


plants,  with  axillary  and  scape-like  one-flowered  peduncles.  —  Ex. 
Dichondra. 

848.  Subord.  Cuscutineae.  Ovary  two-celled ;  the  capsule  open- 
ing by  circumscissile  dehiscence  or  bursting  irregularly.  Embryo 
filiform,  and  spirally  coiled  in  fleshy  albumen,  destitute  of  cotyle- 
dons !  Parasitic,  leafless,  twining  herbs,  destitute  of  green  color 
(135).  Stamens  usually  furnished  with  fringed  scales  within. — 
Ex.  Cuscuta  (Dodder). 

849.  Ord.  SoIanaceJB  (the  Nightshade  Family)  diflers  from  Scroph- 
ulariacese  chiefly  in  the  regular  (rarely  somewhat  irregular)  flow- 
ers, with  as  many  fertile  stamens  as  there  are  lobes  to  the  corolla 
(four  or  five),  and  the  plaited  or  valvate  aestivation  of  the  corolla. 
Fruit  either  capsular  or  baccate.  Embryo  small,  mostly  curved, 
in  fleshy  albumen.  —  Ex.  Solanum  (Potato),  Nicotiana.  The  fruit 
of  Datura  is  spuriously  four-celled.  —  Distinguished  from  Scrophu- 
lariacese  by  their  regular  flowers  and  plaited  aestivation.  Stimu- 
lant narcotic  properties  pervade  the  order,  the  herbage  and  fruits 
of  which  are  mostly  deleterious,  often  violently  poisonous,  and 
furnishing  some  of  the  most  active  medicines ;  such  as  the  To- 
bacco, the  Henbane  (Hyoscyamus  niger),  the  Belladonna  (Atropa 


937  938  941 

Belladonna),  the  Thorn-apple  or  Jamestown  Weed  (Datura  Stra- 


FIG.  935.  Flower  of  Tobacco  (Nicotiana  Tabacum).  936.  The  capsule,  dehiscent  at  the 
apex,  with  the  persistent  calyx.  937.  Cross-section  of  the  same.  938.  Magnified  section  of 
the  seed  of  Solanum.  939.  Flowers  and  berries  of  Solanum  Dulcamara.  940.  Flower  of  Hyos- 
cyamus niger.    941.  Fruit  (pyxis,  616)  of  the  same. 


454 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


monium),  and  the  Bittersweet  (Solanum  Dulcamara)  ;  the  last 
only  slightly  narcotic.  Yet  the  berries  of  some  Solanums  are  eat- 
able when  cooked  (as  Tomatoes,  the  Egg-Plant,  &c.),  and  the 
starchy  tubers  of  the  Potato  are  an  important  article  of  food.  But 
the  fruit  and  seeds  of  Capsicum  (Cayenne pepper)  are  stimulant. 

850.  Ord.  Gentianaceae  [the  Gentian  Family).  Herbs,  with  a 
watery  juice ;  the  leaves  opposite  and  entire.  Flowers  regular, 
often  showy.  Calyx  of  usually  four  or  five  persistent,  more  or 
less  united  sepals.  Corolla  mostly  convolute  in  sestivation  ;  the 
stamens  inserted  on  its  tube.  Ovary  one-celled,  with  two  parietal, 
but  often  introflexed,  placentae ;  styles  united  or  none.  Capsule 
many-seeded.  Seeds  with  fleshy  albumen  and  a  minute  embryo. 
—  Ex.  Gentiana,  Frasera  (the  American  Columbo).  A  pure  bit- 
ter and  tonic  principle  [Gentianine)  pervades  the  whole  order. 
Gentiana  lutea  of  Middle  Europe  furnishes  the  officinal  Gentian, 
for  which  almost  any  of  our  species  may  be  substituted. 

851.  Subord.  Menyanthi 'efe  {the  Bucklean  Family)  has  alternate, 
sometimes  trifoliolate  or  toothed  leaves,  and  a  valvate-induplicate 
sestivation  of  the  corolla.  —  Ex.  Menyanthes,  Limnanthemum  (this 
bears  the  peduncles  on  the  petiole,  Fig.  949). 


852.  Subord.  Obolarieae  has  an  imbricative  sestivation  of  the  co- 


fig.  942.  Flower  of  Gentiana  angiisti folia.  943.  Corolla,  and  944,  the  calyx,  laid  open. 
945.  The  pistil.  946.  Cross-sectiitn  of  the  pistil,  showing  the  parietal  attachment  of  the  ovules. 
947.  Ripe  capsule  of  G.  Saponaria,  raised  on  a  stipe :  the  persistent  withering  corolla,  &c.,  torn 
away.  94S.  A  magnified  seed,  with  its  large  and  loose  testa.  949.  Leaf  of  Limnanthemum 
(Villarsia),  bearing  the  flowers  on  its  petiole. 


THE    MONOPETALOUS    ORDERS. 


455 


rolla,  opposite  leaves,  and  the  whole  internal  surface  of  the  ovary 
ovuliferous  !  —  Ex.  Obolaria. 

853.  Ord.  ApocynacecE  (the  Dogbane  Family).  Trees,  shrubs,  or 
herbs,  with  milky  juice,  and  opposite  entire  leaves,  without  stipules. 
Flowers  regular.  Calyx  five-cleft,  persistent.  Corolla  five-lobed, 
twisted  in  aestivation.  Filaments  distinct ;  the  anthers  sometimes 
slightly  connected :  pollen  granular.  Ovaries  two,  distinct,  or 
rarely  united,  but  their  styles  or  stigmas  combined  into  one  :  in 
fruit  usually  forming  two  follicles.  Seeds  often  with  a  coma. 
Embryo  large  and  straight,  in  sparing  albumen.  —  Ex.  Apocynum 
(Dog's-bane,  Fig.  950),  Vinca  (Periwinkle)  ;  and  a  great  number 
of  tropical  shrubs  and  trees.  In  all,  the  juice  is  drastic  or  poison- 
ous, and  often  yields  caoutchouc ;  which  in  Sumatra  is  obtained 
from  Urceola  elastica.  The  well  known  Nux  vomica  is  the  seed 
of  Strychnos  Nux-vomica  of  India.  S.  toxifera  yields  the  famous 
Woorari  poison  of  Guiana.  One  kind  of  Upas  is  obtained  from 
the  bark  of  the  root  of  S.  Tieute  in  Java.  The  poisonous  princi- 
ple in  these  plants  is  an  alkaloid,  called  Strychnia. 


854.  Ord.  AsclepiadaceSB  {the  Milkweed  Family).  Herbs  or  shrubs, 
with  milky  juice,  and  opposite  entire  leaves  ;  mainly  differing  from 
the  preceding  order  (as  they  do  from  all  other  Exogenous  plants) 
by  the  peculiar  connection  of  the  stamens  with  the  stigma,  and  the 
cohesion  of  the  pollen  into  wax-like  masses,  which  are  attached  in 


FIG.  950.  Apocynum  androsaemi folium.  951,  Flower  of  the  natural  size.  952.  Stamena 
with  the  anthers  connivent  around  the  pistils.  953.  The  pistils  with  their  large  common 
stigma.    954.  Seed  with  its  coma,  or  tuft  of  silky  hairs. 


456 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


pairs  to  five  glands  of  the  stigma,  and  removed  from  the  anther- 
cells  usually  by  the  agency  of  insects.  Fruit  consisting  of  two 
follicles.  Seeds  usually  with  a  silky  coma.  —  Ex.  Asclepias  (Milk- 
weed, Wild  Cotton).  The  juice  of  A.  tuberosa  (Pleurisy-root, 
Butterfly- weed)  is  not  milky.  In  all,  it  is  bitter  and  acrid,  and 
contains  caoutchouc. 


855.  Ord.  JasminaceaB  {the  Jessamine  Family)  consists  of  a  few 


FIG.  955.  Flower-bud  oflhe  common  Milkweed  (Asclepias  Cornuti).  956.  Expanded  flower; 
the  calyx  and  corolla  reflexed ;  showing  the  stamineal  crown.  957.  One  of  the  hooded  appen- 
dages of  the  latter  removed  and  seen  sidewise,  with  its  included  process  or  horn.  9.58.  A  verti- 
cal section  of  a  flower  (the  hooded  appendages  removed)  through  the  tube  of  stamens,  the  thick 
stigma,  ovaries,  &c.  959.  Flower  with  the  calyx,  and  the  fertilized  enlarging  ovaries,  crowned 
with  the  large  stigma  common  to  the  two,  from  the  angles  of  the  peltate  summit  of  which  the 
pairs  of  pollen-masses,  detached  from  the  anther  cells,  hang  by  their  stalks  or  caudicle  from  a 
gland.  [See  page  315 :  Fig.  420.  An  anther,  from  which  the  hooded  appendage  is  cut  away. 
421.  One  more  magnified:  its  two  pollen-masses  still  in  the  open  cells,  but  attached  by  their 
stalks  each  to  one  of  the  glands,  to  which  a  pollen-mass  of  an  adjacent  stamen  on  each  side  is 
already  similarly  attached.  422.  One  of  these  pairs  of  pollen  masses  separate.  423.  Pollen- 
masses  of  Asclepias  incarnata,  connected  by  their  emitted  pollen-tubes  (much  mignified)  with 
the  stigma.  424.  Section  through  the  stigma  and  into  one  of  the  styles,  sliowing  the  course  of 
the  pollen-tubes.]  960.  Fruit  (follicle)  of  the  Common  Milkweed.  961.  Cross-section  of  the 
last,  in  an  early  state.  962.  Detached  placenta  in  fruit,  covered  with  seeds.  963.  Seed  (cut 
across),  with  its  coma.  964.  Section  of  the  seed  as  it  lies  in  963,  parallel  with  the  cotyledons. 
965.  Vertical  section  of  the  seed  perpendicular  to  the  face  of  the  cotyledons. 


THE  APETALOUS  ORDERS.  457 

chiefly  Asiatic  shrubs,  with  compound  leaves  and  fragrant  flowers ; 
differing  from  Oleacese  by  the  imbricated  or  twisted  aestivation  of 
the  hypocrateriform  corolla,  erect  seeds,  &c.  —  Ex.  Jasminutn, 
the  Jessamine.  Cultivated  for  ornament,  and  for  their  very  fra- 
grant blossoms. 

856.  Subord.  Bolivarieffi  consists  of  a  few  American  (three  of 
them  Texan)  plants,  and  one  from  the  Cape  of  Good  Hope,  some- 
times with  simple  leaves,  and  scarcely  differing  from  the  true 
Jasminacese  ;  though  some  of  them  have  four  ovules  in  each  cell. 

857.  Ord.  Oleaceffi  {the  Olive  Family).  Trees  or  shrubs,  with 
opposite  leaves,  either  simple  or  pinnate.  Calyx  persistent.  Co- 
rolla four-cleft,  or  of  four  separate  petals,  valvate  in  aestivation, 
sometimes  none.  Stamens  mostly  two,  adnate  to  the  base  of  the 
corolla.  Ovary  free,  two-celled,  with  two  pendulous  ovules  in 
each  cell.  Fruit  by  suppression  usually  one-celled  and  one-  or 
two-seeded.  Seed  albuminous.  Embryo  straight.  —  Ex.  Olea 
(the  Olive),  and  Chionanthus  (Fringe-tree),  where  the  fruit  is  a 
drupe.  Syringa,  the  Lilac,  which  has  a  capsular  fruit.  Fraxinus, 
the  Ash ;  where  the  fruit  is  a  samara,  the  flowers  are  polygamous, 
and  often  destitute  of  petals.  Olive  oil  is  expressed  from  the  es- 
culent drupes  of  Olea  Europaea.  The  bark,  like  that  of  the  Ash, 
is  bitter,  astringent,  and  febrifugal.  Manna  exudes  from  the  trunk 
of  Fraxinus  Ornus  of  Southern  Europe,  &c.  —  Forestiera,  of  doubt- 
ful affinity,  is  perhaps  to  follow  this  order,  although  entirely  apet- 
alous. 


Division  III.  —  Apetalous  Exogenous  Plants.* 

Corolla  none  ;  the  floral  envelopes  consisting  of  a  single  series 
(calyx),  or  sometimes  entirely  wanting. 

Conspectus  of  the  Orders. 

Group  1.  Flowers  perfect,  with  a  conspicuous  or  colored  mostly  adnate  ca- 
lyx. Ovary  several-celled  and  many-ovuled.  Capsule  or  berry  many- 
seeded. —  Herbs  or  climbing  shrubs.  Aristolochiace^,  p.  459. 

*  Numerous  plants  of  the  Polypetalous  orders  are  apetalous,  such  as  Clem- 
atis, Anemone,  and  other  Ranunculaceae,  some  Rhamnacea?,  Caryophyllaceae, 
Onagraceae,  Portulacaceae,  Crassulacese,  Rosaceae,  Aceracese,  &c.  Also  some 
Oleacese  and  Primulaceae  of  the  Gamopetalous  series  are  apetalous. 

39 


458  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Group  2.  Flowers  perfect,  or  rarely  polygamous,  with  a  regular  and  often 
petaloid  calyx.  Ovary  free.  Ovules  solitary  in  each  ovary  or  cell.  Em- 
bryo curved  or  coiled  around  mealy  albumen,  rarely  in  the  axis  or  exal- 
buminous.  —  Chiefly  herbs. 

Ovary  several-celled,  consisting  of  a  whorl  of  several  one-ovuled  carpels. 

PuYTOLACCACEiE,  p.  460. 

Ovary  one-celled,  with  a  single  ovule. 

Stipules  none.     Ovule  campy lotropous  or  amphitropous. 

Calyx  herbaceous.  Chenopodiace^,  p.  461. 

Calyx  and  bracts  scarious.  Amarantaceje,  p.  462. 

Calyx  corolline,  the  persistent  base  indurated.       Nyctaginaceje,  p.  462. 
Stipules  sheathing  (ochrea;).     Calyx  corolline.     Ovule  orthotropous. 

PoLYGONACE^,  p.  462. 

Group  3.     Flowers  perfect,  polygamous  or  dioecious,  not  disposed  in  aments, 

with  a  regular,  and  often  petaloid  calyx.     Ovary  one-celled,  or  rarely 

two-celled,  with  one  or  few  ovules  in  each  cell :  but  the  fruit  one-celled 

and  one-seeded.     Embryo  not  coiled  around  albumen.  —  Trees  or  shrubs. 

*  Style  or  stigma  one. 

Calyx  free  from  the  ovary,  and  not  enveloping  the  fruit. 

Flowers  polygamo-dioecious.    Anth.  opening  by  valves.  Laurace^,  p.  463. 
Flowers  perfect.     Anthers  opening  longitudinally.      Thymelaceje,  p.  464. 
Calyx  free,  but  baccate  in  fruit  and  inclosing  the  achenium. 

Eleagnace.«:,  p.  464. 
Calyx  adnate  to  the  ovary. 

Ovules  several,  pendulous  from  a  stipe-like  placenta.   SANXALACEiE,  p.  465. 
Ovule  solitary,  suspended. 

Parasitic  shrubs.     Ovule  without  integuments.       LoranthacejE,  p.  466. 

Trees.     Fruit  a  drupe.  Nyssace^,  p.  465. 

*  *  Styles  or  stigmas  two,  divergent.  Ulmace^,  p.  466. 

Group  4.  Flowers  perfect,  entirely  destitute  of  calyx  as  well  as  corolla.  Em- 
bryo minute,  inclosed  in  the  persistent  embryo-sac  at  the  apex  of  the  albu- 
men. —  Herbs  or  suffrutescent  plants.  Saururace^,  p.  467. 

Group  5.  Flowers  perfect  or  diclinous,  frequently  destitute  of  both  calyx  and 
corolla.  —  Submersed  or  floating  aquatic  herbs. 

Flowers  monoecious.    Fruit  one-celled  and  one-seeded. 

Ceratophyllace^,  p.  468. 
Flowers  mostly  perfect.     Fruit  four-celled  and  four-seeded.  • 

Callitrichaceje,  p.  468. 
Flowers  mostly  perfect.     Capsule  several-celled,  several-seeded. 

Podostemace^,  p.  469. 

Group  6.  Flowers  monoecious  or  dioecious,  not  amentaceous.  Fruit  capsular 
or  drupaceous,  with  two  or  more  cells,  and  one  (or  rarely  two)  seeds  in 
each.  —  Herbs,  shrubs,  or  trees. 

Fruit  mostly  dry.    Juice  milky.    Pollen  simple.  Eophorbiace^,  p.  469. 

Fruit  drupaceous.    Pollen-grains  quaternary.  Empeteace^,  p.  470, 


THE    APETALOXJS    ORDERS. 


459 


Group  7.  Flowers  monoecious  or  dioecious ;  the  sterile,  and  frequently  the 
fertile  also,  in  aments,  or  in  heads  or  spikes.  Ovary  often  two-  to  several- 
celled,  but  the  fruit  always  one-celled.  —  Trees,  shrubs,  or  (only  in  Urti- 
caceae)  herbs. 

*  Fruit  drupaceous.     Calyx  adherent.  Jcglandace;e,  p.  471. 

*  *  Fruit  a  nut,  involucrate.     Calyx  adherent.  Cupuliferje,  p.  471. 

*  «  «    Fruit  one-seeded,  indehiscent.      Fertile  and  sterile  flowers  both  in 

aments,  and  entirely  destitute  of  calyx. 
Ovary  one-celled  ;  ovule  solitary,  erect.  Myricace^,  p.  472. 

Ovary  two-celled,  two-ovuled:  ovule  pendulous.  BEXuLACEiE,  p.  472. 

*  *  *  *  Fruit  dehiscent,  many-seeded.    Seeds  with  a  coma.    Fertile  and  ster- 

ile flowers  both  in  aments,  and  destitute  of  calyx.         SALicACEiE,  p.  473. 

«  «  *  «  *  Fruit  a  nut  or  a  two-celled  and  few-seeded  capsule.     Fertile  and 

sterile  flowers  both  in  aments  or  heads,  and  destitute  of  calyx. 
Capsule  two-beaked,  many-seeded.  BALSAMiFLUiE,  p.  474. 

Nut  club-shaped,  one-seeded,  bristly-downy.  Platanaceje,  p.  474. 

«««««*  Fruit  an  achenium,  often  inclosed  in  a  baccate  calyx.  Flowers 
variously  disposed,  sometimes  collected  in  fleshy  heads.  —  Juice  milky, 
when  trees  or  shrubs.  Urticace^,  p.  474. 

858.  Ord.  AristolochiaceSB  (the  Birthwort  Family).     Herbaceous, 


FIG.  966.  Asarum  Canadense.  967.  Calyx  displayed,  and  a  vertical  section  through  the 
rest  of  the  flower.  968.  Crosa-section  of  the  ovary ;  the  upper  portion  (from  which  the  limb  of 
the  calyx  is  cut  away)  showing  the  stamens,  the  united  styles,  &c.  969.  A  separate  stamen, 
enlarged.    970.  Vertical  section  of  a  seed. 


460 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


or  climbing  shrubby  plants,  with  alternate  leaves.  Flowers  brown 
or  greenish,  usually  solitary.  Calyx-tube  more  or  less  united  with 
the  ovary  ;  the  limb  valvate.  Stamens  six  to  twelve,  epigynous, 
or  adherent  to  the  base  of  the  short  and  thick  style  :  anthers  ad- 
nate,  extrorse.  Stigmas  radiate.  Ovary  3-6-celled.  Capsule  or 
berry  three-  to  six-celled,  many-seeded.  Embryo  minute,  in 
fleshy  albumen.  —  Ex.  Asarum  (Wild  Ginger,  Canada  Snake- 
root),  Aristolochia  (Virginia  Snake-root).  Pungent,  aromatic,  or 
stimulant  tonics  ;  generally  termed  Snake-roots,  being  reputed  an- 
tidotes for  the  bites  of  venomous  snakes.* 

859.  Ord.  Phytolaccacese  {the  Poke-weed  Family).     Chiefly  repre- 


sented by  the  common  Poke  (Phytolacca  decandra),  which  has  a 


*  The  Ord.  RAFFLESIACE^,  and  perhaps  other  RHIZANTHEiE, 
consisting  of  most  remarkable  fungus-like  parasites  (136,  and  Fig.  125)  are  to 
be  placed  somewhere  in  this  vicinity. 

FIG.  988,  989,  Phytolacca  decandra  (Poke).  990.  A  flower.  991.  Unripe  fruit.  992. 
Cross-section  of  the  same,  a  little  enlarged.  993.  Magnified  seed.  994.  Section  of  the  same 
across  the  embryo.  995.  Vertical  section,  showing  the  embryo  coiled  around  the  albumen  into 
a  ring.    996.  IMagnified  detached  embryo. 


THE  APETALOUS  ORDERS. 


461 


compound  ovary  of  ten  confluent  (one-seeded)  carpels,  the  short 
styles  or  stigmas  distinct ;  the  fruit  a  flattened  berry.  The  root  is 
acrid  and  emetic :  yet  the  young  shoots  in  the  spring  are  used  as 
a  substitute  for  Asparagus.  The  berries  yield  a  copious  deep- 
crimson  juice.  Other  genera  connect  the  order  with  the  next ;  but 
are  distinguished,  when  the  stamens  are  of  the  same  number  as  the 
sepals,  by  their  position  alternate  with  them,  as  in  Portulacacese. 

860.  Ord,  ChenopodiaceiB  {the  Goosefoot  Family).  Chiefly  weedy 
herbs,  with  alternate  and  more  or  less  succulent  leaves,  and  small 
herbaceous  flowers.  Calyx  sometimes  tubular  at  the  base,  persist- 
ent ;  the  stamens  as  many  as  its  lobes,  or  fewer,  and  inserted  at 
their  base.  Ovary  free,  one-celled,  with  a  single  ovule  arising 
from  its  base.  Fruit  a  utricle  or  achenium.  Embryo  curved  or 
coiled  around  the  outside  of  mealy  albumen,  or  spiral,  without  any 
albumen  (in  Salsola,  &c.).  —  Ex,  Chenopodium,  Atriplex,  Beta 
(the  Beet),  &c.  Sea-side  plants,  or  common  weeds  :  some  are 
pot-herbs,  such  as  Spinach  :  a  few  are  cultivated  for  their  esculent 
roots ;  as  the  Beet,  which  contains  sugar.  Soda  is  largely  extract- 
ed from  the  maritime  species,  especially  from  those  of  Salsola  and 
Salicornia  (Samphire,  Glass-wort).  Chenopodium  anthelminticum 
yields  the  Worm-seed  oil. 


974  975 


FIG.  971.  Part  of  the  spike  of  Salicornia  herbacea :  the  flowers  placed  three  together  in  ex- 
cavations of  the  stem,  protected  by  a  fleshy  scale.  972.  Separate  flower.  973.  A  flower  of 
Blitum,  with  its  fleshy  calyx  and  single  stamen.  974.  Same,  more  enlarged,  with  the  thick- 
ened juicy  calyx  (975)  removed.  976.  The  ripe  fruit.  977.  Same,  divided  vertically,  showing 
the  embryo  coiled  around  the  central  albumen.  978.  Flower  of  Chenopodium  album  (common 
Goosefoot).  979.  Section  of  the  same,  more  enlarged.  980.  Section  of  the  utricle  and  seed, 
showing  the  embryo.  981.  Calyx  of  Salsola  kali  (Saltwort),  in  fruit,  with  its  wing-like  border. 
982.  Section  of  the  same,  bringing  the  ovary  mto  view.  933.  The  spirally  coiled  embryo  of 
Chenopodina  maritima. 

39* 


462 


EXOGENOUS    OR    DICOTYLEDONOUS   PLANTS. 


861.  Ord.  AmarantaceSB  {the  Amaranth  Family).  Herbs,  with 
opposite  or  alternate  leaves ;  the  flowers  in  heads,  spikes,  or  dense 
clusters,  imbricated  with  dry  and  scarious  bracts  which  are  usually- 
colored.  Calyx  of  three  to  five  sepals,  which  are  dry  and  scari- 
ous, like  the  bracts.  Stamens  five  or  more,  hypogynous,  distinct 
or  monadelphous  :  anthers  frequently  one-celled.  Embryo  annu- 
lar, always  vertical.  Otherwise  nearly  as  in  Chenopodiacese.  — 
Ex.  Amarantus,  Gomphrena,  &c.  Weeds.  A  few  Amaranths 
are  cultivated  for  their  dry  and  enduring  richly-colored  flowers. 

862.  Ord.  Nyctaginacese.  Herbs  or  shrubs,  with  opposite  leaves  ; 
distinguished  by  their  tubular  and  in  fund  ibuli  form  calyx,  the  upper 
part  of  which  resembles  a  corolla,  and  at  length  separates  from 
the  base,  which  hardens  and  incloses  the  one-celled  achenium-like 
fruit,  appearing  like  a  part  of  it.  Stamens  hypogynous,  1  -  20. 
Embryo  coiled  around  the  outside  of  mealy  albumen.  Flowers 
involucrate,  often  showy.  Mirabilis  (Four-o'clock)  has  a  one- 
flowered  involucre  exactly  like  a  calyx,  while  the  latter  resem- 
bles the  corolla  of  a  Morning-Glory.  Plants  of  warm  latitudes ; 
many  on  our  Southwestern  frontiers. 

863.  Ord.  PolygonaceSB  {the  Buckwheat  Family).     Herbs  with  al- 


FIG.  984.    Polygonum  Pennsylvanicum.    985.  Flower  laid  open.    986.  Section  of  the  ovary, 
showing  the  erect  ovule.    987.  Section  of  the  seed,  showing  the  embryo,  at  one  side  of  albumen. 


THE  APETALOUS  ORDERS. 


463 


ternate  leaves ;  remarkable  for  their  stipules  (ochrese,  304),  which 
usually  form  sheaths  around  the  stems  above  the  leaves,  and  for 
their  orthotropous  ovules.  Stamens  definite,  inserted  on  the  peta- 
loid  calyx.  Fruit  achenium-like,  compressed  or  triangular.  Em- 
bryo curved,  or  nearly  straight,  applied  to  the  outside  (rarely  in 
the  centre)  of  starchy  albumen.  —  Ex.  Polygonum,  Rumex  (Dock, 
Sorrel),  Rheum  (Rhubarb).  The  stems  and  leaves  of  Rhubarb 
and  Sorrel  are  pleasantly  acid  :  while  several  Polygonums  (Knot- 
weed,  Smart-weed,  Water  Pepper,  &c.)  are  acrid  or  rubefacient. 
The  farinaceous  seeds  of  P.  Fagopyrum  (the  Buckwheat)  are  used 
for  food.  The  roots  of  most  species  of  Rhubarb  are  purgative : 
but  it  is  not  yet  known  what  particular  species  of  Tartary  yield 
the  genuine  officinal  article.  The  Eriogoneje  (of  southern  and 
western  North  America)  form  a  tribe  remarkable  for  their  exstipu- 
late  leaves  and  involucrate  flowers. 

864.  Ord.  LauraceSB  (the  Laurel  Family).  Trees  or  shrubs,  with 
pellucid-punctate  alternate  leaves,  their  margins  entire.  Flowers 
sometimes  polygamo-dicecious.  Calyx  of  four  to  six  somewhat 
united  petaloid  sepals,  which  are  imbricated  in  two  series,  free 
from  the  ovary.  Stamens  definite,  but  usually  more  numerous 
than  the  sepals,  inserted  on  the  base  of  the  calyx :  anthers  two-  to 
four-celled,  opening  by  recurved  valves !  Fruit  a  berry  or  drupe, 
the  pedicel  often  thickened.     Seed  with  a  large  almond-like  em- 


bryo, destitute  of  albumen.  —  Ex.    Laurus,  Sassafras,  Benzoin. 
All  aromatic  plants,  almost  every  part  abounding  in  warm  and 


FIG.  997.  A  staminate,  and  993,  a  pistillate  flower  of  Sassafras.  999.  A  stamen  with  its 
glands  at  the  base :  the  anthers  opening  by  two  sets  of  valves.  1000.  Pistil ;  the  ovary  divided. 
1001.  Branch  in  fruit.     1002.  Section  of  the  drupe  and  seed. 


464 


EXOGENOUS    OR   DICOTYLEDONOUS   PLANTS. 


Stimulant  volatile  oil,  to  which  their  qualities  are  due.  Camphor 
is  obtained  fronn  Camphora  officinarum  of  Japan,  China,  &c. 
Cinnamon  is  the  bark  of  Cinnamomum  Zeylanicum  ;  Cassia  Bark^ 
of  Cinnamomum  aromaticum  of  China.  The  aromatic  bark  and 
wood  and  the  very  mucilaginous  leaves  of  our  own  Sassafras  are 
well  known.  Our  Benzoin  odoriferum  is  the  Spice-wood,  or  Fever- 
bush.  Laurus  nobilis  is  the  true  Laurel,  or  Sweet  Bay.  Persea 
gratissima,  of  the  West  Indies,  bears  the  edible  Avocado  pear. 

865.  Ord.  Thymelacese  {the  Mezereum  Family).  Shrubby  plants, 
with  perfect  flowers,  and  a  very  tough  bark  ;  the  tube  of  the  peta- 
loid  calyx  being  free  from  the  (one-ovuled)  ovary ;  its  lobes  im- 
bricated in  aestivation  ;  the  pendulous  seed  destitute  of  albumen. 
Stamens  often  twice  as  many  as  the  lobes  of  the  calyx,  inserted 
upon  its  tube  or  throat.  — Ex.  Daphne,  &c.,  of  Europe  and  Mid- 
dle Asia  ;  and  Dirca  (Leather- wood.  Moose-wood,  Wickopy), 
which  is  the  only  North  American  genus.  The  tough  bark  is 
acrid,  or  even  blistering,  and  is  also  useful  for  cordage.  The 
reticulated  fibres  may  be  separated  into  a  kind  of  lace  in  the  La- 
getta  or  Lace-bark  of  Jamaica.  The  fruit  of  all  the  species  is 
deleterious. 


866.  Ord.  EleagnaceSB  {the  Oleaster  Family).  Shrubs  or  small 
trees,  with  the  flowers  more  commonly  dioecious,  the  leaves  either 
opposite  or  alternate  ;  readily  distinguished  from  the  preceding  by 


FIG.  1008.    Flowering  branch  of  Dirca  palustria.    1009.  A  flower.     1010.  The  same,  laid 
open  and  enlarged.     1011.  Branch  in  fruit. 


THE    APETALOUS    ORDERS. 


466 


having  the  foliage  and  shoots  covered  with  scurf,  hy  the  ascending 
albuminous  seed,  and  the  persistent  tube  of  the  calyx,  which,  al- 
though free  from  the  ovary,  becomes  succulent,  like  a  berry  in 
fruit,  and  constricted  at  the  throat,  inclosing  the  crustaceous  ache- 
nium  !  —  Ex.  Eleagnus,  Shepherdia  ;  cultivated  for  their  silvery 
foliage.     The  fruit  is  sometimes  eaten. 

867.  Ord.  SanlalaceSB  (the  Sandal-wood  Family).  Trees,  shrubs, 
or  sometimes  herbs ;  with  alternate  entire  leaves,  and  small  (very 
rarely  dioecious)  flowers.  Calyx-tube  adherent  to  the  ovary ;  the 
limb  four-  or  five-cleft,  valvate  in  sestivation ;  its  base  lined  with  a 
fleshy  disk,  the  edge  of  which  is  often  lobed.  Stamens  as  many 
as  the  lobes  of  the  calyx,  and  opposite  them,  inserted  on  the  edge 
of  the  disk.  Ovules  several,  destitute  of  proper  integuments,  pen- 
dulous from  the  apex  of  a  stipe-like  basilar  placenta.  Style  one. 
Fruit  indehiscent,  crowned  with  the  limb  of  the  calyx.  Seed  albu- 
minous. Embryo  small.  —  Ex.  Comandra,  Pyrularia,  &c.  The 
fragrant  Sandal-wood  is  obtained  from  several  Indian  and  Polyne- 
sian species  of  Santalum.  The  large  seeds  of  Pyrularia  oleifera 
(Buffalo-tree,  Oil-nut)  would  yield  a  copious  fixed  oil. 


868.  Ord.  NyssacefB  (the  Tupelo  Family).  Trees,  with  dioecio- 
polygamous  flowers,  diflTering  from  the  last  in  the  solitary  ovule 
suspended  from  the  summit  of  the  cell,  and  furnished  with  integu- 
ments in  the  ordinary  manner.     Style  one,  stigmatose  down  one 


FIG.   1003.    Branch  of  Comandra  umbellata.     1004.  Enlarged  flower  laid  open.    1005.  Verti- 
section  of  a  flower.     1006.  One  of  the  segments  of  the  calyx,  enlarged,  showing  the  lufl  of 
hairs  which  connects  its  surface  with  the  anther !    1007,  The  fruit,  reduced  in  size. 


466 


EXOGENOUS    OR   DICOTYLEDONOUS   PLANTS. 


side.  Drupe  baccate.  Embryo  large  in  sparing  albumen.  —  Con- 
sists only  of  the  genus  Nyssa.  The  Black  Gum-tree,  &c.,  is  re- 
markable for  the  toughness  of  the  interlaced  fibres,  so  that  it  is 
very  difficult  to  split  the  timber.  The  acid  berries  give  the  name 
of  Sour  Gum  to  Nyssa  capitata. 

869.  Ord.  LoranthaceiS  {the  Mistletoe  Family)^  consists  of  shrubby 
plants,  with  articulated  branches,  and  opposite  coriaceous  and  dull 
greenish  entire  leaves,  parasitic  on  trees.  The  floral  envelopes 
are  various.  In  Mistletoe  (which  is  dioecious)  the  anthers  are  ses- 
sile and  adnate  to  the  face  of  the  sepals,  one  to  each.  The  ovary 
is  one-celled,  with  a  single  suspended  ovule,  consisting  of  a  nucleus 
without  integuments.  Fruit  a  one-seeded  berry.  Embryo  small, 
in  fleshy  albumen.  —  Ex.  Loranthus;  Viscum,  the  Mistletoe,  from 
the  glutinous  berries  of  which  birdlime  is  made.  The  bark  is  as- 
tringent. 

870.  Ord.  Ulmacea;  {the  Elm  Family).  Trees  or  shrubs,  with  a 
watery  juice,  and  alternate  rough  leaves,  furnished  with  deciduous 


1015  1014  1020  lots 

stipules.     Flowers  in  axillary  clusters  or  fascicles,  rarely  solitary, 


FIG.  1012.  Flower  of  the  Slippery  Elm.  1013.  Calyx  laid  open  and  the  ovary  divided  verti- 
cally. 1014.  Fruit,  the  cell  laid  open  to  show  the  single  seed.  1015,  The  latter  magnified. 
1016.  Its  embryo. 

FIG.  1017.  Branch  of  Celtis  Americana,  in  flower.  1018.  Enlarged  flower,  divided  vertical- 
ly.   1019.  Drupe,  the  flesh  divided  to  show  the  stone,     1020.  The  coiled  embryo. 


THE  APETALOUS  ORDERS. 


467 


perfect  or  polygamous.  Calyx  campanulate,  four-  or  five-cleft, 
free  from  the  ovary  ;  the  lobes  imbricated  in  aestivation.  Stamens 
inserted  on  the  base  of  the  calyx,  as  many  as  its  lobes  and  oppo- 
site" them,  or  more  numerous.  Ovary  one-  or  two-celled,  with  a 
single  suspended  ovule  in  each  :  styles  or  stigmas  two.  Fruit  one- 
celled  and  one-seeded,  either  a  samara  with  a  straight  embryo  and 
no  albumen,  as  in  the  Elm  (Ulmus) ;  or  a  drupe  with  a  curved  em- 
bryo and  scanty  albumen,  as  in  Celtis  (Hackberry),  the  type  of  the 
suborder  or  tribe  Celtideje.  Timber-trees.  The  inner  bark  of  the 
Slippery  Elm  is  charged  with  mucilage.     Hackberries  are  edible. 


871.  Ord.  SaururaceEB  {the  Lizard' s-tail  Family).     Herbs  (grow- 
ing in  swampy  places),  with  the  stems  jointed  at  the  nodes  ;  the 

FIG.  1020.  Saumrus  cernuus.  1021.  A  separate  flower,  with  its  bract  and  a  part  of  the 
axi3  magnified.  1022.  A  more  magnified  anther,  discharging  its  pollen  from  one  cell.  1023. 
Cross-section  of  the  ovary.  1024.  Vertical  section  of  on§  of  the  carpels  in  fruit,  and  of  the  con- 
tained seed,  with  the  sac  at  the  extremity  of  the  albumen,  containing  the  minute  embryo. 
1025.  A  seed.  1026.  Same,  with  the  outer  integument  (testa)  removed,  showing  the  sac  of  the 
amnios.  1027.  The  latter,  highly  magnified.  1028.  Section  of  the  same,  showing  the  inclosed 
heart-shaped  embryo. 


468 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


leaves  alternate,  entire,  with  somewhat  sheathing  petioles  ;  the 
flowers  perfect,  in  racemes  or  spikes,  destitute  of  all  floral  envel- 
opes. Stamens  definite.  Ovary  composed  of  three  to  five,  more 
or  less  united,  few-ovuled  carpels,  with  distinct  styles  or  stigmas. 
Capsule  or  berry  with  usually  a  single  seed  in  each  cell.  Embryo 
heart-shaped,  minute,  inclosed  in  the  persistent  embryo-sac,  at  the 
apex  of  the  albumen  !  —  Ex.  Saururus  (Lizard's-tail).  Slightly 
pungent  plants.  They  are  scarcely  distinct  from  the  Pepper 
Family.* 

872.  Ord.  CeratophyllaceSB  {the  Homwort  Family),  consists  of  the 
single  genus  Ceratophyllum  (growing  in  ponds  and  streams  in 
many  parts  of  the  world)  ;  distinguished  by  the  whorled  and  dis- 
sected leaves  with  filiform  segments ;  the  flowers  monoecious,  and 
sessile  in  the  axil  of  the  leaves ;  the  stamens  indefinite,  with  sessile 
anthers ;  and  the  simple  one-celled  ovary,  which  forms  a  beaked 
achenium  in  fruit,  containing  an  orthotropous  suspended  seed,  with 
four  cotyledons  !  and  a  manifest  plumule. 

873.  Ord.  CallitrichaceSB  (the  Water- Starwort  Family),  formed  of 


*  Ord.  PIPERACE^  (the  Pepper  Family),  a  chiefly  tropical  order  with 
the  embryo  inclosed  in  the  persistent  embryo-sac,  differing  from  Saururaceae 
principally  in  the  one-celled  simple  ovary,  with  a  solitary  ovule  (fruit  a  berry), 
and  the  extrorse  anthers ;   the  leaves  often  opposite  or  whorled ;  the  jointed 


FIG.  1029.  Callitrlche  verna,  about  the  natural  size.  1030.  Perfect  fldwers,  magnified. 
1031.  A  staminate  and  a  pistillate  flower,  magnified.  1032.  The  fruit.  10.33.  Cross-section  of 
the  fruit.    1034.  Vertical  section  through  the  pericarp,  seeds,  and  embryo. 


THE  APETALOUS  ORDERS.  469 

the  genus  Callitriche  ;  aquatic  annuals,  with  opposite  entire  leaves  ; 
the  axillary  flowers  (either  perfect  or  monoecious)  with  a  two- 
leaved  involucre,  but  entirely  destitute  of  calyx  and  corolla ;  sta- 
men one  (or  rarely  two),  hypogynous,  with  a  slender  filament,  and 
a  reniform  one-celled  anther;  the  ovary  four-lobed,  four-celled, 
indehiscent  in  fruit ;  the  seeds  albuminous. 

874.  Ord.  PodostemaceSB  {the  River-weed  Family)  comprises  a 
few  (American  and  Asiatic)  aquatics,  with  the  aspect  of  Mosses  or 
Hepaticae ;  their  small  flowers  arising  from  a  kind  of  spathe  ;  the 
calyx  often  entirely  wanting  ;  the  stamens  frequently  reduced  to 
one,  or  two  and  monadelphous ;  the  ovary  two-  or  three-celled, 
with  distinct  styles;  in  fruit  forming  a  ribbed  capsule,  containing 
numerous  exalbuminous  seeds  attached  to  a  central  column.  —  Ex. 
Podostemum. 

875.  Ord.  EuphorbiaceSB  (the  Spurge  Family).  Herbs,  shrubs,  or 
even'trees,  often  with  a  milky  juice  :  in  northern  temperate  climes 
chiefly  represented  by  the  genus  Euphorbia  (Fig.  344-349); 
which  is  remarkable  for  having  numerous  staminate  flowers,  re- 
duced to  a  single  stamen  (484),  inclosed  in  an  involucre  along 
with  one  pistillate  flower,  reduced  to  a  compound  pistil,  and  also 
achlamydeous,  or  with  an  obsolete  calyx.  But  other  genera  have 
a  .regular  calyx  both  to  the  staminate  and  pistillate  flowers ;  and  a 
few  are  likewise  provided  with  petals.  Ovary  of  two  to  nine  more 
or  less  united  carpels,  coherent  to  a  central  prolongation  of  the 
axis :  styles  distinct,  often  two-cleft.  Fruit  mostly  capsular,  sep- 
arating into  its  elementary  carpels,  or  cocci  (usually  leaving  a  per- 
sistent axis),  which  commonly  open  elastically  by  one  or  both 
sutures.  Seed  with  a  large  embryo  in  fleshy  albumen,  suspended. 
—  Ex.  Euphorbia  (Spurge),  Croton,  Buxus  (the  Box).  Acrid 
and  deleterious  qualities  pervade  this  large  order,  chiefly  resident 
in  the  (usually)  milky  juice.  But  the  starchy  accumulations  in 
the  rhizoma,  or  underground  portion  of  the  stem,  as  in  the  Man- 
dioc  or  Cassava  (Janipha  Manihot)  oY  tropical  America,  are  per- 
fectly innocuous,  when  freed  from  the  poisonous  juice  by  washing 

stems  sometimes  woody,  but  scarcely  exhibiting  annual  layers.  They  all 
possess  stimulant,  aromatic,  and  pungent  qualities,  the  common  Pepper  (the 
dried  berries  of  the  Indian  Piper  nigrum)  representing  the  ordinary  properties 
of  the  order.  The  intoxicating  Betel  of  the  Malays  consists  of  the  leaves  of 
Piper  Betle.  The  .^va  of  the  Society  and  Sandwich  Islands,  from  which  an 
inebriating  drink  is  made,  is  Piper  methysticum. 

40 


470 


EXOGENOUS    OR   DICOTYLEDONOUS    PLANTS. 


and  exposure  to  heat.  The  starch  thus  obtained  is  the  Cassava, 
which,  when  granulated,  forms  the  Tapioca  of  commerce.  The 
farinaceous  albumen  of  the  seed  is  also  innocent,  and  the  fixed 
oil  which  it  frequently  contains  is  perfectly  bland.  But  the  oil 
procured  by  expression  abounds  in  the  juices  of  the  embryo  and 
integuments  of  the  seed,  and  poss^ses  more  or  less  active  proper- 
ties. The  seeds  of  Ricinus  communis  yield  the  Castor  Oil :  and 
those  of  Croton  Tiglium,  and  some  other  Indian  species,  yield  the 
violently  drastic  Croton  oil  or  Oil  of  Tiglium.  Some  plants  of 
the  family  are  most  virulent  poisons  ;  as,  for  example,  the  Manchi- 
neal-tree  of  the  West  Indies  (Hippomane  Manicella),  which  is  said 
even  to  destroy  persons  who  sleep  under  its  shade ;  and  a  drop  of 
the  juice  falling  upon  the  hand  produces  an  instantaneous  blister. 
The  hairs  of  some  species  (such  as  Jatropha  stimulosa)  sting  like 
Nettles.  The  hard  and  close-grained  wood  of  the  Box  is  inval- 
uable to  the  wood-engraver.  The  purple  dye  called  Turnsole 
is  derived  from  Crozophora  tinctoria.  Another  most  important 
product  of  this  order  is  caoutchouc,  which  is  yielded  by  various 
plants  of  different  families  ;  but  the  principal  supply  of  the  article 
(that  of  Para,  Demarara,  and  Surinam)  is  furnished  by  the  tree 
named  Hevea  Guianensis  by  Aublet,  the  Siphonia  elastica  of  Per- 
soon. 


876.  Ord.  Empetracece  {the  Crowherry  Family).     Low,  shrubby 


FIG.  1035.  Branch  cf  Ceratiola  ericoides  in  fruit.  1036.  Magnified  staminate  flower,  with 
it3  bracts.  1037.  The  two  stamens,  with  an  inner  bract  or  sepal.  1038.  Magnified  pistillate 
flower,  with  its  imbricated  bracts.  1039.  The  pistil  separate ;  one  of  the  cells  laid  open  by  a 
Tcrtical  section,  showing  the  erect  ovule.     1040.  Drupe,  with  the  persistent  scales  at  the  base. 

1041.  Transverse  section  of  its  endocarp,  or  two  nucules,  with  the  inclosed  seed  and  embryo. 

1042.  Vertical  section  of  the  seed. 


THE  APETALOUS  ORDEKS.  471 

evergreens,  with  the  aspect  of  Heaths ;  the  leaves  crowded  and 
acerose,  with  small  (dioecious  or  polygamous)  flowers  produced  in 
the  axils  of  the  uppermost.  Calyx  consisting  of  regular  imbricated 
sepals,  or  represented  by  imbricated  bracts.  Stamens  few  :  pollen 
of  four  grains  coherent  in  one,  as  in  Heaths.  Ovary  three-  to 
nine-celled,  with  a  single  erect  ovule  in  each  cell :  style  short  or 
none  :  stigmas  lobed  and  often  laciniated.  Fruit  a  drupe,  with 
from  three  to  nine  bony  nucules.  Seeds  albuminous ;  the  radi- 
cle inferior.  —  Ex.  Empetrum,  Ceratiola,  Corema  ;  unimportant 
plants. 

877.  Ord.  Juglandaccffi  {the  Walnut  Family).  Trees,  with  alter- 
nate pinnated  leaves,  and  no  stipules.  Flowers  monoecious.  Ster- 
ile flowers  in  aments,  with  a  membranous  irregular  calyx,  and  in- 
definite stamens.  Fertile  flowers  few,  clustered,  with  the  calyx 
adherent  to  the  incompletely  two-  to  four-celled  but  one-ovuled 
ovary,  the  limb  small,  three-  to  five-parted  ;  sometimes  with  as 
many  small  petals.  Ovule  orthotropous.  Fruit  drupaceous ;  the 
epicarp  fibrous-fleshy  and  coherent,  or  else  coriaceous  and  dehis- 
cent :  endocarp  bony.  Seed  four-lobed,  without  albumen.  Em- 
bryo oily  :  cotyledons  corrugate,  2-cleft.  —  Ex.  Juglans  (Walnut, 
Butternut),  Carya  (Hickory,  Pecan,  &c.).  —  The  greater  part 
of  the  order  is  North  American.  The  timber  is  valuable  ;  es- 
pecially that  of  Black  Walnut,  for  its  rich  dark-brown  color  when 
polished ;  that  of  Hickory,  for  its  great  elasticity  and  strength. 
The  young  fruit  is  acrid :  the  often  edible  seeds  abound  in  a  dry- 
ing oil. 

878.  Ord.  CupulifcrSB  {the  Oak  Family).  Trees  or  shrubs,  with 
alternate  and  simple  straight-veined  leaves,  and  deciduous  stipules. 
Flowers  usually  monoecious.  Sterile  flowers  in  aments,  with  a 
scale-like  or  regular  calyx,  and  the  stamens  one  to  three  times  the 
number  of  its  lobes.  Fertile  flowers  solitary,  two  to  three  togeth- 
er, or  in  clusters,  furnished  with  an  involucre  which  incloses  the 
fruit  or  forms  a  cupule  at  its  base.  Ovary  adnate  to  the  calyx,  and 
crowned  by  its  minute  or  obsolete  limb,  two-  to  six-celled  with  one 
or  two  pendulous  ovules  in  each  cell :  but  the  fruit  is  a  one-celled 
and  one-seeded  nut  (585).  Seed  without  albumen.  Embryo  with 
thick  and  fleshy  cotyledons,  which  are  sometimes  coalescent.  — 
Ex.  Quercus  (the  Oak),  Fagus  (the  Beech),  Corylus  (the  Hazel- 
nut), Castanea  (the  Chestnut),  &;c.  Some  of  the  principal  forest- 
trees  in  northern  temperate  regions.     Their  valuable  timber  and 


472 


EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 


edible  seeds  are  too  well  known  to  need  enumeration.  The  as- 
tringent bark  and  leaves  of  the  Oak  abound  in  tannin,  gallic  acid, 
and  a  bitter  extractive  called  Quercine ;  they  are  used  in  tanning 
and  dyeing.  Quercitron  is  obtained  from  the  Quercus  tinctoria. 
Galls  are  swellings  on  the  leafstalks,  &c.,  when  wounded  by  cer- 
tain insects ;  those  of  commerce  are  derived  from  Q.  infectoria 
of  Asia  Minor.  Cork  is  the  exterior  bark  of  the  Spanish  Quercus 
Suber. 


879.  Ord.  Myricacesc  {the  Sweet-Gale  Family).  Shrubs,  with  al- 
ternate and  simple  aromatic  leaves,  dotted  with  resinous  glands ; 
monoecious  or  dioecious.  Differs  from  the  next  principally  by  the 
one-celled  ovary,  with  a  single  erect  orthotropous  ovule,  and  a 
drupe-like  nut.  —  Ex.  Myrica,  Comptonia,  the  Sweet  Fern.  The 
drupes  of  M.  cerifera  (our  Candleberry)  yield  a  natural  wax. 

880.  Ord.  Betulaceae  (the  Birch  Family).  Trees  or  shrubs,  with 
alternate  and  simple  straight-veined  leaves,  and  deciduous  stipules. 
Flowers  monoecious  ;  those  of  both  kinds  in  aments  and  commonly 
achlamydeous,  placed  three  together  in  the  axil  of  each  three-lobed 


Flfr.  1042.  Quercus  Chinquapin  in  fruit:  a,  cluster  of  sterile  aments.  1043.  A  magnified 
staminate  flower.  1044.  Transverse  section  of  an  ovary,  showing  the  three  cells  with  two 
ovules  in  each.  1045.  The  immature  seed,  with  the  accompanying  abortive  ovule.  1046.  The 
But  (acorn),  in  its  scaly  involucre,  or  cupule.  1047.  Vertical  section  of  the  same,  and  of  the 
included  seed  and  embryo,  showing  the  thick  cotyledons. 


THE    APETALOUS    ORDERS. 


473 


bract.  Stamens  definite.  Ovary  two-celled,  each  cell  with  one 
suspended  ovule  :  styles  or  stigmas  distinct.  Fruit  membrana- 
ceous or  samara-like,  one-celled  and  one-seeded,  forming  with  the 
three-lobed  bracts  a  kind  of  strobile.  Albumen  none.  —  Ex.  Be- 
tula  (the  Birch),  Alnus  (Alder).  The  bark  is  sometimes  astrin- 
gent, and  that  of  the  Birch  is  aromatic.  The  peculiar  odor  of 
Russia  leather  is  said  to  be  owing  to  a  pyroUgneous  oil  obtained 
from  Betula  alba. 


881.  Ord.  SalicaceiE  (the  Willow  Family).  Trees  or  shrubs,  with 
alternate  simple  leaves,  furnished  with  stipules.  Flowers  dioe- 
cious ;  both  kinds  in  aments,  and  destitute  of  floral  envelopes  (ach- 
lamydeous),  one  under  each  bract.  Stamens  two  to  several,  some- 
times monadelphous.  Ovary  one-celled,  many-ovuied  !  Styles  or 
stigmas  two,  often  two-cleft.  Fruit  a  kind  of  follicle  opening  by 
two  valves.     Seeds  numerous,  ascending,  furnished  with  a  silky 


FIG.  1048.  Ament  of  staminate  flowers  of  Betula  fruticosa?  1049.  One  of  the  three  lobed 
scale?!  of  the  same  enlarged,  showing  the  flowers  (stamens)  on  the  inner  side.  1050.  Ament  of 
pistillate  flowers.  1051.  Branch  in  fruit.  10-52.  One  of  the  scales  with  its  three  flowers  (pis- 
tils) seen  from  within.  1053.  Magnified  section  of  one  of  the  two-celled  pistils,  displaying  the 
ovule  suspended  from  the  summit  of  each  cell.  1054.  The  pistils  (with  their  subtending  bract) 
in  a  more  advanced  state.  1055.  Magnified  cross-section  of  one  of  the  ovaries.  1056.  The  ma- 
lure  fmit,  with  the  cell  divided  vertically;  the  single  seed  occupying  the  cavity;  a  mere  trace 
of  the  other  cell 'leing  visible.     1057.  The  seed  removed.     1058.  The  embryo, 

40* 


474  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

coma!  Albumen  none.  —  Ex.  Salix  (Willow,  already  illustrated, 
473,  Fig.  326-329),  and  Populus  (the  Poplar).  Trees  with  light 
and  soft  wood  :  the  slender  flexible  shoots  of  several  Willows  are 
employed  for  wicker-work.  The  bark  is  bitter  and  tonic  ;  con- 
taining a  peculiar  substance  (Salicine),  which  possesses  febrifugal 
qualities.  The  buds  of  several  Poplars  exude  a  fragrant  balsamic 
resin. 

882.  Ord.  BalsamifluSB  (the  Sweet-Gum  Family)  consists  of  a  sin- 
gle genus  of  three  or  four  species  (natives  of  Eastern  India,  the 
Levant,  and  North  America)  :  which  are  trees,  with  alternate  pal- 
mately-lobed  leaves,  and  deciduous  stipules ;  the  monoecious  flow- 
ers in  rounded  aments  or  heads,  destitute  of  floral  envelopes  ;  the 
indurated  capsules  and  scales  forming  a  kind  of  strobile  ;  the  for- 
mer two-celled,  two-beaked,  opening  between  the  beaks,  several- 
seeded  :  the  seeds  with  a  little  albumen.  It  has  recently  been 
referred  to  the  order  Hamamelacese  (799).  —  Ex.  Liquidambar, 
or  Sweet-Gum :  so  called  from  the  fragrant  balsam  or  Slorax  it 
exudes. 

883.  Ord.  PlatanaceiE  {the  Plane-tree  Family)  consists  of  the  sin- 
gle genus  Platanus  (Plane-tree,  Button-ball),  with  one  Asiatic  and 
one  or  more  North  American  species :  which  are  fine  trees,  with  a 
watery  juice,  and  alternate  palmately-lobed  leaves,  with  sheathing 
stipules.  Flowers  in  globose  amentaceous  heads  ;  both  kinds  des- 
titute of  floral  envelopes.  Fruit  a  one-seeded  club-shaped  little 
nut,  the  base  furnished  with  bristly  hairs.     Seed  albuminous. 

884.  Ord.  UrticaceSB  (the  Nettle  Family).  Trees  or  shrubs  with 
milky  juice,  or  herbs  with  a  watery  juice.  Leaves  often  stipulate. 
Flowers  monoecious,  dioecious,  or  polygamous,  sometimes  collect- 
ed in  aments  or  fleshy  heads,  furnished  with  a  regular  calyx.  Sta- 
mens definite.  Ovary  free  from  the  calyx,  simple,  with  a  solitary 
ovule.  Fruit  an  achenium  or  utricle,  often  inclosed  in  a  fleshy  or 
baccate  calyx.  The  order  comprises  the  following  principal  divis- 
ions :  — 

885.  Subord.  ArtOCarpeOB  (the  Bread-fruit  Family).,  which  are 
trees  or  shrubs  with  a  milky  or  yellow  juice ;  the  flowers  mostly 
aggregated  into  fleshy  heads,  and  forming  a  compound  baccate 
fruit,  or  else  inclosed  in  a  dry  or  succulent  involucre.  Albumen 
none.- — Ex.  Artocarpus  (the  Bread-fruit),  Antiaris  (Upas):  all 
tropical. 

886.  Subord.  MoreSB  (the  Mulberry  Family) ;  which  are  shrubs  or 


THE    APETALOUS    ORDERS.  475 

trees,  very  rarely  herbs,  with  a  milky  juice ;  the  staminate  and 
pistillate  flowers  either  in  separate  aments  or  spikes,  or  often  inter- 
mixed and  included  in  the  same  hollow  and  closed  fleshy  receptacle 
(as  in  the  Fig)  :  the  calyx,  &c.,  becoming  succulent,  and  forming 
a  compound  fruit.  Seeds  albuminous.  —  Ex.  Morus  (the  Mulber-* 
ry.  Fig.  244-246),  Madura  (the  Osage  Orange),  Ficus  (the  Fig, 
Fig.  241-243)  :  nearly  all  tropical. 

887.  Subord.  UrticeSB  (the  proper  Nettle  Family) ;  which  are 
herbs  in  colder  countries,  but  often  shrubs  or  trees  in  the  tropics, 
with  a  watery  juice,  often  with  stinging  hairs  ;  the  flowers  mostly 
loose,  spicate,  or  panicled  ;  the  achenium  usually  surrounded  by  a 
dry  and  membranous  calyx.  Embryo  straight,  in  fleshy  albumen. 
—  Ex.  Urtica  (the  Nettle),  Parietaria. 

888.  Subord,  CaiinabineSB  {the  Hemp  Family) ;  which  are  annual 
erect  herbs,  or  perennial  twining  plants,  with  a  watery  juice  ;  the 
staminate  flowers  racemose  or  panicled ;  the  pistillate  glomer- 
ate, or  imbricated  with  bracts,  and  forming  a  kind  of  strobile-like 
ament.  Embryo  curved:  albumen  none. — Ex.  Cannabis  (the 
Hemp),  Humulus  (the  Hop) :  natives  of  northern  temperate  re- 
gions. 

8!^9.  The  fruit  in  this  large  and  polymorphous  family  is  mostly 
innocent  and  edible,  at  least  when  cooked  ;  while  the  milky  juice 
is  more  or  less  acrid  or  deleterious.  It  also  abounds  in  caout- 
chouc ;  much  of  which  is  obtained  from  some  South  American 
trees  of  this  order,  and  from  Ficus  elastica  in  Java.  In  one  in- 
stance, however,  the  milky  juice  is  perfectly  innocent ;  that  of  the 
famous  Cow-tree  of  South  America,  which  yields  copiously  a  rich 
and  wholesome  milk.  One  of  the  most  virulent  of  poisons,  the 
Bohon  Upas,  is  the  concrete  juice  of  Antiaris  toxicaria  of  the  Indian 
Archipelago.  The  Bread-fruit  is  the  fleshy  receptacle  and  multi- 
ple fruit  of  Artocarpus.  Fustic  is  the  wood  of  the  South  Ameri- 
can Morus  tinctoria.  The  resin  called  Gum  Lac  exudes  and  forms 
small  grains  on  the  branches  of  the  celebrated  Banyan-tree  (Ficus 
Indica,  Fig.  119).  Nettles  are  remarkable  for  their  stinging  ven- 
omous hairs,  and  tough  fibres  of  the  stem,  which,  as  in  those  of 
Hemp,  are  used  for  cordage.  The  leaves  of  the  Hemp  are  stimu- 
lant and  narcotic,  and  are  extensively  used  in  the  East  for  intoxi- 
cation. Hops  are  the  catkins  of  Humulus  Lupulus;  the  bitter  and 
sedative  principle  chiefly  resides  in  the  yellow  grains  that  cohere 
to  the  scales  and  cover  the  fruit. 


476  EXOGENOUS    OR    DICOTYLEDONOUS    PLANTS. 

Subclass  2.     Gymnospermous  Exogenous  Plants. 

890.  Ovules,  and  consequently  the  seeds,  naked,  that  is,  not  in- 
closed in  an  ovary  (560)  ;  the  carpel  being  represented  either  by 
an  open  scale,  as  in  Pines ;  or  by  a  more  evident  leaf,  as  in  Cy- 
cas ;  or  else  wanting  altogether,  as  in  the  Yew. 

891.  Ord.  ConiferSB  (the  Pine  Family).  Trees  or  shrubs,  with 
branching  trunks,  abounding  in  resinous  juice  (the  wood  chiefly 
consisting  of  a  tissue  somewhat  intermediate  between  ordinary 
woody  fibre  and  vessels,  which  is  marked  with  circular  disks) ;  the 
leaves  mostly  evergreen,  scattered  or  fascicled,  usually  rigid  and 
needle-shaped  or  linear,  entire.  Flowers  monoecious  or  dioecious, 
commonly  amentaceous.  Staminate  flowers  consisting  of  one  or 
more  (often  monadelphous)  stamens,  destitute  of  calyx  or  corolla, 
arranged  on  a  common  rachis  so  as  to  form  a  kind  of  loose  ament. 
—  The  particular  structure  of  the  flowers  and  fruit  varies  in  the 
subordinate  groups  chiefly  as  follows  :  — 

892.  Subord.  Abietinese  {the  Fir,  or  proper  Pine  Family).  Fer- 
tile aments  formed  of  imbricated  scales ;  which  are  the  flat  and 
open  carpels,  and  bear  a  pair  of  ovules  adherent  to  their  base,  with 
the  foramen  turned  downwards.  Scales  subtended  by  bracts. 
Fruit  a  strobile  or  cone  (619).  Integument  of  the  seed  coriaceous 
or  woody,  more  or  less  firmly  adherent  to  the  scale.  Embryo  in 
the  axis  of  fleshy  albumen,  with  two  to  fifteen  cotyledons.  (Illus- 
trated in  Fig.  391  -401,  p.  307.) 

893.  Subord.  CuprcssineSB  {the  Cypress  Family).  Fertile  aments 
of  few  scales  crowded  on  a  short  axis,  or  more  numerous  and  pel- 
tate (Fig.  402),  not  bracteate.  Ovules  one,  two,  or  several,  borne 
on  the  base  of  the  scale,  erect  (the  foramen  looking  towards  its 
apex,  Fig.  394).  Fruit  an  indurated  strobile,  or  fleshy  and  with 
the  scales  concreted,  forming  a  kind  of  drupe.  Integument  of  the 
seed  membranous  or  bony.  Cotyledons  two  or  more.  Anthers  of 
several  parallel  cells,  placed  under  a  shield-like  connectivum.  — 
Ex.  Cupressus  (Cypress),  Taxodium  (American  Cypress),  Juni- 
perus  (Juniper,  Red  Cedar). 

894.  Subord.  Taxinese  {the  Yew  Family).  Fertile  flowers  solitary, 
terminal,  consisting  merely  of  an  ovule,  forming  a  drupaceous 
seed  at  maturity.  There  are,  therefore,  no  strobiles  and  no  car- 
pellary  scales.  Embryo  with  two  cotyledons.  —  Ex.  Taxus 
(the  Yew),  Torreya. 


ENDOGENOUS    OR    MONOCOTYLEDONOUS    PLANTS.  477 

895.  It  is  unnecessary  to  specify  the  important  uses  of  this  large 
and  characteristic  family,  which  comprises  the  most  important  tim- 
ber-trees of  cold  countries,  and  also  furnishes  resinous  products  of 
great  importance,  such  as  turpentine^  resin,  pitch,  tar,  Canada  bal- 
sam (obtained  from  the  Balsam  Fir),  &c.  The  terebinthine  Juni- 
per-berries are  the  fruit  of  Juniperus  communis.    The  Larch  yields 

Venetian  turpentine.  The  powerful  and  rubefacient  Oil  of  Savin 
is  derived  from  J.  Sabina  of  Europe  :  for  which  our  J.  Virgin- 
iana  (Red  Cedar)  may  be  substituted.  The  leaves  of  the  Yew  are 
narcotic  and  deleterious.  The  bark  of  Hemlock  and  Larch  is  used 
for  tanning. 

896.  Orel.  Cycadacese  (the  Cycas  Family).  Tropical  plants,  with 
an  unbranched  cylindrical  trunk,  increasing,  like  Palms,  by  a  sin- 
gle terminal  bud  ;  the  leaves  pinnate  and  their  segments  rolled  up 
from  the  apex  (circinate)  in  vernation,  in  the  manner  of  true  Ferns. 
Flowers  dioecious ;  the  staminate  in  a  strobile  or  cone  ;  the  pistil- 
late also  in  strobiles,  or  else  (in  Cycas)  occupying  contracted  and 
partly  metamorphosed  leaves ;  the  naked  ovules  borne  on  its  mar- 
gins.—  Ex.  Cycas,  Zamia,  the  dwarf  Florida  species  of  which  is 
illustrated  in  Fig.  403-409,  p.  308.  —  A  kind  of  Arrowroot  is 
obtained  from  these  thickened  stems ;  and  a  sort  of  Sago  from  the 
trunk  of  Cycas. 


Class  II.     Endogenous  or  Monocotyledonous  Plants. 

897.  Stem  not  distinguishable  into  bark,  pith,  and  wood ;  but  the 
latter  consisting  of  bundles  of  fibres  and  vessels  irregularly  imbed- 
ded in  cellular  tissue ;  the  rind  firmly  adherent ;  no  medullary 
rays,  and  no  appearance  of  concentric  layers :  increase  in  diame- 
ter effected  by  the  deposition  of  new  fibrous  bundles,  which,  at 
their  commencement  at  least,  occupy  the  central  part  of  the  stem. 
Leaves  seldom  falling  off  by  an  articulation,  commonly  sheathing 
at  the  base,  usually  alternate,  entire,  and  with  simple  parallel 
veins  (nerved).  Floral  envelopes  when  present  mostly  in  threes; 
the  calyx  and  corolla  frequently  undistinguishable  in  texture  and 
appearance.  Embryo  with  a  single  cotyledon  ;  or  if  the  second 
is  present,  it  is  much  smaller  than  the  other  and  alternate  with 
it  (634). 


478  endogenous  or  monocotyledonous  plants. 

Conspectus  of  the  Orders. 

Group  1.  Flowers  on  a  spadix,  furnished  with  a  double  perianth  (calyx  and 
corolla).  Ovary  one-  to  three-celled,  with  a  single  ovule  in  each  cell» 
Embryo  in  hard  albumen,  —  Trees  with  unbranched  columnar  trunks. 

Palm^,  p.  479* 

Group  2.  Flowers  on  a  spadix ;  with  the  perianth  simple,  scale-like,  or 
commonly  altogether  wanting.  —  Chiefly  herbs. 

Terrestrial,  mostly  with  a  spathe.     Fruit  baccate.  Arace^,  p.  480. 

Terrestrial.  Fruit  nut-like,  one-seeded.  Typhace^,  p.  481. 
Aquatic  (floating  or  immersed). 

Flowers  from  the  edge  of  the  floating  frond.  Lemnace^,  p.  481. 

Flowers  axillary  or  on  a  spadix.  Naiadace^,  p.  482. 

Group  3.  Flowers  not  spadiceous,  furnished  with  a  double  perianth  (calyx 
and  corolla).  'Ovaries  several,  distinct  or  sometimes  united,  free. — 
Aquatic  herbs.  Alismace^,  p.  482. 

Group  4.  Flowers  with  a  simple  or  double  perianth,  adherent  to  the  ovary 
(ovary  inferior),  either  completely  or  partially.  —  Herbs. 

*  Perianth  regular.     Ovary  one-celled,  with  parietal  placentae,  or  rarely  three- 

to  six-celled,  with  the  placentae  in  the  axis. 
Dioecious  or  polygamous  ;  aquatic.  HyDROCHARiDACEiE,  p.  483. 

Flowers  perfect;  terrestrial.  Burmanniace^,  p.  483. 

*  *  Perianth  irregular.     Ovary  one-celled,  with  parietal  placentse.     Stamens 

one  or  two,  adherent  to  the  style  (gynandrous).       Orchidace^,  p.  483. 

*  *  «  Perianth  irregular.  Ovary  three-celled.  Perfect  stamens  usually  one. 
Fertile  stamen  1,  inferior.  ZiNciBERACEiE,  p.  484. 
Fertile  stamen  1,  superior,  Cannaceje,  p.  485. 
Fertile  stamens  mostly  5,  the  sixth  abortive.  MusACEiE,  p.  485. 

*  *  *  «  Perianth  regular,  or  sometimes  a  little  irregular.     Ovary  three-celled, 

many-ovuled  (in  Tillandsia  free,  in  Lophiola  nearly  so).     Stamens  either 
three  or  six. 
Anthers  introrse.     Stamens  mostly  6. 

Bulbous.  Amaryllidace^,  p.  486. 

Not  bulbous:  rootsfibrous:  leaves  indurated  or  scurfy    Bromeliace^,  p.485, 

and  HffiMODORACEJE,  p.  485. 

Anthers  extrorse.     Stamens  3.  Iridace^,  p.  486. 

»  *  *  «  *  Perianth  regular.     Ovary  three-celled,  with  one  or  two  ovules  in 

each.     Flowers  dioecious.     Stamens  six.  Dioscoreace^,  p.  487. 

Group  5.  Flowers  with  a  regular  perianth,  which  is  more  or  less  petaloid 
(the  two  series  when  present  are  similar),  or  rarely  glumaceous,  and  free 
from  the  ovary.     Embryo  inclosed  in  albumen. 

Perianth  not  glumaceous. 

Anthers  introrse.     Styles  or  stigmas  separate.  Smilace^,  p.  487. 


ENDOGENOUS  OR  MONOCOTYLEDONOTJS  PLANTS.       479 

Anthers  introrse.     Styles  united  into  one. 

Terrestrial,  not  spathaceous.     Flower  regular.  Liliace/e,  p,  487. 

Aquatic,  spathaceous.    Flower  oflener  irregular.  Pontederiace.e,  p.  488. 

Anthers  extrorse  (except  Tofieldia).  Melanthace^,  p.  488. 

Perianth  glumaceous.  Jcncaceje,  p.  489. 

Group  6.  Flowers  with  a  double  or  imbricated  perianth  :  the  exterior  herba- 
ceous or  glumaceous ;  the  inner  petaloid,  free  from  the  one-  to  three-celled 
ovary.  Seeds  orthotropous ;  the  embryo  at  the  extremity  of  the  albumen 
farthest  from  the  hilum. 

Flowers  perfect.     Sepals  herbaceous.  Commelynace^,  p.  490. 

Flowers  perfect,  capitate.    Sepals  and  bracts  glumaceous.    Xyridace^,  p.  490. 

Flowers  moncEcious  or  dicecious,  capitate.  Eriocaulonaceje,  p.  490. 

Group  7.  Flowers  imbricated  with  bracts  (glumes)  and  disposed  in  spikelets; 
the  proper  perianth  none  or  rudimentary.  Ovary  one-celled,  one-ovuled. 
Embryo  at  the  extremity  of  the  albumen  next  the  hilum. 

Sheaths  closed.     Glume  or  bract  single.  CvPERACEiE,  p.  490. 

Sheaths  open.     Glumes  in  pairs.  Gramine^,  p.  491. 

898.  Ord.  Palma;  {Palms).  Chiefly  trees,  with  unbranched  cylin- 
drical trunks,  growing  by  a  terminal  bud.  Leaves  large,  clustered, 
fan-shaped  or  pinnated,  plaited  in  vernation.  Flowers  small,  per- 
fect or  polygamous,  mostly  with  a  double  (6-merous)  perianth  ; 
the  stamens  usually  as  many  as  the  petals  and  sepals  together. 
Ovary  1-3-celled,  with  a  single  ovule  in  each  cell.  Fruit  a  drupe 
or  berry.  Seeds  with  cartilaginous  albumen,  often  hollow  ;  the 
embryo  placed  in  a  small  separate  cavity.  —  Ex.  Palms,  the  most 
majestic  race  of  plants  within  the  tropics,  and  of  the  highest  value 
to  mankind,  are  scarcely  found  beyond  the  limits  of  these  favored 
regions.  The  Date-tree  (Phoenix  dactylifera,  the  leaves  of  which 
are  the  Palms  of  Scripture),  a  native  of  Northern  Africa,  endures 
the  climate  of  the  opposite  shore  of  the  Mediterranean :  while  in 
the  New  World,  Chamserops  Palmetto  (Fig.  166),  the  only  arbo- 
rescent species  of  the  United  States,  and  one  or  two  low  Palms  with 
a  creeping  caudex  (Dwarf  Palmettoes),  extend  from  Florida  to 
North  Carolina.  Palms  afford  food  and  raiment,  wine,  oil,  wax, 
flour,  sugar,  salt,  thread,  weapons,  utensils,  and  habitations.  The 
Cocoa-nut  (Cocos  nucifera)  is  perhaps  the  most  important,  as  well 
as  the  most  widely  diffused  species.  Besides  its  well-known  fruit, 
and  the  beverage  it  contains,  the  hard  trunks  are  employed  in  the 
construction  of  huts ;  the  terminal  bud  (as  in  our  Palmetto  and 
other  Cabbage  Palms)  is  a  delicious  article  of  food  ;  the  leaves  are 
used  for  thatching,  for  making  hats,  baskets,  mats,  fences,  for 


480 


j:NDOGENOirS    OR    MONOCOTYLEDONOUS    PLANTS. 


torches,  and  for  writing  upon  ;  the  stalk  and  midrib  for  oars  ;  their 
ashes  yield  abundance  of  potash  ;  the  juice  of  the  flowers  and 
stems  (replete  with  sugar,  which  is  sometimes  separated  under  the 
name  of  Jagery)  is  fermented  into  a  kind  of  wine,  or  distilled  into 
Arrack;  from  its  spathes  (as  from  some  other  Palms),  when 
wounded,  flows  a  grateful  laxative  beverage,  known  in  India  by 
the  name  of  Toddy  ;  the  rind  of  the  fruit  is  used  for  culinary  ves- 
sels ;  its  tough,  fibrous,  outer  portion  is  made  into  very  strong  cor- 
dage ( Coir  rope) ;  and  an  excellent  fixed  oil  is  copiously  expressed 
from  the  kernel.  Sago  is  procured  from  the  trunks  of  many 
Palms,  but  chiefly  from  species  of  Sagus  of  Eastern  India.  Canes 
and  Rattans  are  the  slender,  often  prostrate,  stems  of  species  of 
Calamus.  The  Phytelephas  of  South  America  yields  the  larger 
sort  of  nuts,  the  hard  and  white  albumen  of  which  is  the  vegetable 
ivory ^  now  so  largely  used  by  the  turner. 


899.  Ord.  AraceSB  {the  Arum  Family).  Herbs,  with  a  fleshy 
corm  or  rhizoma,  occasionally  shrubby  or  climbing  plants  in  the 
tropics;  the  leaves  sometimes  compound  or  divided,  frequently 
with  more  or  less  reticulated  veins.  Flowers  mostly  on  a  spadix 
(often  naked  at  the  extremity)  usually  surrounded  by  a  spathe. 
Flowers  commonly  monoecious,  and  destitute  of  envelopes,  or  with 
a  single  perianth.     Ovary  one-  to  several-celled,  with  one  or  more 


FIG.  1059  Branch  of  the  inflorescence  of  Chamoerops  Hystrix  (Blue  Palmetto).  1060.  A 
sterile  flower.  1061.  Perfect  flower,  with  the  calyx  and  corolla  removed.  1062.  Same,  with 
three  of  the  stamens  removed,  so  as  more  distinctly  to  show  the  three  somewhat  united  carpels. 
1063.  One  of  the  carpels  enlarged,  seen  laterally.  1064.  Same,  with  a  section  of  its  inner  face, 
showing  the  ovule  or  young  seed.  1065.  Vertical  section  of  a  young  cocoa-nut,  showing  the 
hollow  albumen ;  and  also  the  small  embryo  in  a  separate  little  cavity.  1066.  Section  of  a 
Palm-stem. 


ENDOGENOUS  OR  MONOCOTYLEDONOCS  PLANTS. 


481 


ovules.  Fruit  a  berry.  Seeds  with  or  without  albumen.  —  Ex. 
Arum,  Calla,  Symplocarpus  (Skunk-Cabbage),  Orontium,  Acorus 
(Sweet  Flag) :  the  three  latter  bear  flowers  furnished  with  a  peri- 
anth. —  All  are  endowed  with  an  acrid  volatile  principle,  which 
is  merely  pungent  and  aromatic  in  Sweet  Flag  (Acorus  Calamus). 


900.  Ord.  Typhacese  {the  Cat-tail  Family)  consists  of  two  genera; 
namely,  Typha  (the  Cat-tail),  and  Sparganium  (Burr-reed),  of  no 
important  use ;  they  are  somewhat  intermediate  between  Araceae 
and  Cyperacese. 

901.  Ord.  LemnaceSB  {the  Duck-weed  Family)^  consisting  chiefly 
of  Lemna  (Duckweed,  or  Water  Flax-seed) ;  floating  plants,  with 
their  roots  arising  from  the  bottom  of  a  flat  frond,  and  hanging 
loose  in  the  water ;  their  flowers  produced  from  the  margin  of  the 
frond,  bursting  through  a  membranous  spathe  ;  the  sterile,  of  one 


FIG.  1067.  Young  leaf,  and  106S,  spathes  and  flowers,  of  Symplocarpus  foelida.  1069.  A. 
separate  flower.  1070.  A  sepal  and  stamen  seen  from  within.  1071.  An  anther  seen  from  the 
front.  1072.  The  spadix  or  collective  head  in  fruit;  a  quarter-section  removed,  showing  sec- 
tions of  the  immersed  seeds.  1073.  A  seed  detached,  of  the  natural  size.  1074.  Section  of  the 
seed,  with  its  large  globular  embryo  and  plumule :  in  this  plant  there  is  no  albumen. 

41 


482 


ENDOGENOUS    OR    MONOCOTYLEDONOUS    PLANTS. 


or  two  Stamens ;   the   fertile,  of  a  one-celled  ovary ;    in  fruit 
utricle  :  they  are  a  kind  of  minute  and  greatly  reduced  Aracese. 


902.  Ord.  NaiadaceaB  (the  Pond-iveed  Family).  Water-plants, 
with  cellular  leaves,  and  sheathing  stipules  or  bases  :  the  flowers 
inconspicuous,  sometimes  perfect.  Perianth  simple  or  none.  Sta- 
mens definite.  Ovaries  solitary,  or  two  to  four  and  distinct,  one- 
seeded.  Albumen  none.  Embryo  straight  or  curved.  —  Ex.  Po- 
tamogeton  (Pond-weed),  Najas,  Ruppia,  Zostera;  the  two  latter  in 
salt  or  brackish  water. 

903.  Ord.  AlismaceSB  {the  Water- Plantain  Family).  Marsh  herbs, 
with  the  leaves  and  scapes  usually  arising  from  a  creeping  rhizo- 
ma ;  the  former  either  linear,  or  bearing  a  flat  limb,  which  is  ribbed 
or  nerved,  but  the  veinlets  commonly  reticulated.  Flowers  regu- 
lar, perfect  or  polygamous,  mostly  in  racemes  or  panicles,  not  on  a 
spadix.  Perianth  double.  Sepals  three.  Petals  three.  Seeds 
solitary  in  each  carpel  or  cell,  straight  or  curved,  destitute  of  albu- 
men. —  Ex.  Alisma  (Water-Plantain),  Sagittaria  (Arrowhead)  ; 
belonging  to  the  proper  Alisma  Family,  which  has  the  seed  (and 
consequently  the  embryo)  curved  or  doubled  upon  itself.  Triglo- 
chin  and  Scheuchzeria  chiefly  constitute  the  suborder  Juncagine^  ; 


FIG.  1075.  Whole  plant  of  Lemna  minor,  magnified,  bearing  a  staminate  monandrous  flow- 
er. 1076.  An  individual  with  a  diandroua  perfect  flower;  which  at  1077  is  seen  separate,  with 
its  spathe,  highly  magnified.  1078.  Flovyer  of  Lemna  gibba,  much  magnified.  1079.  Vertical 
highly  magnified  section  of  the  pistil  and  the  contained  ovule  of  Lemna  minor.  1080.  The 
fruit,  and  1081,  its  section,  showing  the  seed,  1082.  Section  through  the  highly  magnified 
seed  and  large  embryo. 


ENDOGENOUS    OR    MONOCOTYLEDONOUS    PLANTS. 


483 


where  the  seed  and  embryo  are  straight,  and  the  petals  (if  present) 
greenish  like  the  calyx. 


904.  Ord.  nydrocharidacea;  {the  Frog*s-Ut  Family)  consists  of  a 
few  aquatic  herbs,  with  dioecious  or  polygamous  regular  flowers  on 
scape-like  peduncles  from  a  spathe,  and  simple  or  double  floral 
envelopes,  which  in  the  fertile  flowers  are  united  in  a  tube,  and 
adnate  to  the  1  -  6-celled  ovary,  more  commonly  one-celled  with 
three  parietal  placentae.  Seeds  numerous,  without  albumen.  — -  Ex. 
Limnobium,  Vallisneria,  Udora.* 

905.  Ord.  BurmanniaceaB  consists  of  small,  mostly  tropical,  annual 
herbs,  differing  from  Orchidacese  by  their  regular  and  perfect  flow- 
ers with  three  stamens.  —  Ex.  Burmannia,  Apteria,  of  the  South- 
ern States. 

906.  Ord.  OrcMdaceSB  (the  Orchis  Family).  Herbs,  of  varied  as- 
pect and  form ;  distinguished  from  the  other  orders  with  an  adnate 


*  Ord.  BUTOMACEiE  consists  of  Butoraus,  Hydrocleis,  &c. :  plants  re- 
sembling the  Alisma  tribe,  but  with  a  milky  juice,  and  the  numerous  seeds 
attached  to  the  whole  inner  surface  of  the  carpels  ! 

FIG.  1033.  Raceme  or  spike  of  Triglochin  palustre.  1084.  Enlarged  flower,  1085.  A  petal 
and  stamen.  1036.  The  club-shaped  capsule.  1087,  A  magnified  seed,  exhibiting  the  raphe 
and  chalaza.  1088.  Embryo  of  the  same,  showing  the  lateral  slit  just  above  the  radicular  end 
(634,  where  this  structure  is  explained),  1089.  Vertical  section  of  the  same  passing  through 
the  slit,  bringing  the  plumule  to  view.  1090,  Cross-section  (more  magnified),  showing  the  co- 
tyledon wrapped  around  the  plumule. 

FIG.  1091.  Leaf,  and  1092,  flower,  of  Alisma  Plantago.  1093.  More  enlarged  flower,  with 
the  petals  removed.  1094.  Carpel,  with  the  ovary  divided,  showing  the  doubled  ovule.  109.5. 
Vertical  section  of  the  germinating  seed  of  Alisma  Damasonium:  a,  the  cotyledon;  b,  the  plu- 
mule ;  c,  the  protruding  radicle. 


484  ENDOGENOUS    OR   MONOCOTYLEDONOIIS    PLANTS. 

ovary,  and  from  all  other  plants,  by  their  irregular  flowers,  with  a 
perianth  of  six  parts ;  their  single  fertile  stamen  (or  in  Cypripe- 
dium  their  two  stamens)  coherent  with  the  style  (composing  the 
column) ;  their  pollen  usually  combined  into  two  or  more  compact 
or  regular  masses  (pollinia),  or  of  the  consistence  and  appearance 
of  wax :  the  ovary  one-celled,  with  three  parietal  placentse,  cov- 
ered with  numerous  small  seeds.  —  Ex.  Orchis,  Cypripedium 
(Ladies'-Slipper),  Arethusa,  &c.  In  the  tropics  many  are  Epi- 
phytes (132,  Fig.  120).  Many  are  cultivated  for  their  beauty  and 
singularity.  The  tuberiferous  roots  are  often  filled  with  a  very 
dense  mucilaginous  or  glutinous  substance  (as  those  of  our  Aplec- 
trum,  thence  called  Putty-root).  Of  this  nature  is  the  Salep  of 
commerce,  the  produce  of  some  unascertained  species  of  Middle 
Asia.  The  fragrant  Vanilla  is  the  fleshy  fruit  of  the  West  Indian 
Vanilla  claviculata. 


907.  Ord,  ZingiberaceSB   (the   Ginger  Family)  consists  of  some 
tropical  aromatic  herbs,  the  nerves  of  their  leaves  diverging  from 

FIG.  1096.  Orchis  spectabilis :  a,  a  separate  flower.  1097.  Column  (somewhat  magnified), 
from  which  the  other  parts  are  cut  away :  the  two  anther-cells  opening  and  showing  the  pollen- 
masses.  109S.  Magnified  pollen-mass,  with  its  stalk.  1099.  Arethusa  bulbosa.  1100.  The 
column,  enlarged:  the  anther  terminal  and  opening  by  a  lid.  1101.  Magnified  anther,  with 
the  lid  removed,  showing  the  two  pollen-masses  in  each  cell. 


ENDOGENOUS  OR  MONOCOTYLEDONOITS  PLANTS.      485 

a  midrib  ;  the  adnate  perianth  irregular  and  triple  (having  a  corolla 
of  two  series  as  well  as  a  calyx)  ;  fertile  stamen  one,  on  the  ante- 
rior side  of  the  flower,  free ;  the  fruit  a  three-celled  capsule  or 
berry  ;  the  seeds  several :  with  the  embryo  in  a  little  sac  at  one 
extremity  of  the  farinaceous  albumen.  —  There  are,  in  fact,  six 
stamens  in  the  androecium,  the  three  exterior  petaloid  and  forming 
the  so-called  inner  corolla,  and  two  of  the  inner  verticil  are  sterile. 
—  Ex.  Zingiber  (Ginger),  Amomum  (Cardamon).  Stimulant  and 
aromatic.  Some  afford  a  coloring  matter  (TMrmeric).  They  are 
all  showy  plants. 

908.  Ord,  Cannaceae  {the  Arrowroot  Family),  which  are  equally 
tropical  plants,  differ  from  the  preceding  chiefly  in  the  want  of 
aroma,  and  in  having  the  single  fertile  stamen  posterior,  with  a 
one-celled  anther.  —  Ex.  Maranta  arundinacea  (the  Arrowroot) 
of  the  West  Indies ;  the  tubers  of  which  are  filled  with  pure  starch. 

909.  Ord.  Musaceae  {the  Banana  Family).  Tropical  plants,  of 
which  the  Banana  and  Plantain  are  the  type  ;  distinguished  by  their 
simple  perianth  and  five  or  six  perfect  stamens.  The  fruit  is  most 
important  in  the  tropics ;  the  gigantic  leaves  are  used  in  thatch- 
ing ;  and  the  fibres  of  Musa  textilis  yield  Manilla  hemp,  as  well 
as  a  finer  fibre  from  which  a  delicate  linen  is  made. 

910.  Ord.  BromeliaceSB  {the  Pine-Apple  Family)  consists  of  Amer- 
ican and  chiefly  tropical  plants ;  with  rigid  and  dry  channelled 
leaves,  often  with  a  scurfy  surface,  a  mostly  adnate  perianth  of 
three  sepals  and  three  petals,  and  six  or  more  stamens ;  the  seeds 
with  mealy  albumen.  —  Ex.  Ananassa,  the  Pine-Apple  ;  the  fine 
fruit  of  which  is  formed  by  the  consolidation  of  the  imperfect  flow- 
ers, bracts,  and  receptacle  into  a  fleshy,  succulent  mass.  Tilland- 
sia,  the  Black  Moss  or  Long  Moss,  which,  like  most  Bromelias, 
grows  on  the  trunks  and  branches  of  trees  in  the  warmer  and  hu- 
mid parts  of  America,  has  the  ovary  free  from  the  perianth. 

911.  Ord.  Hcemodoraceae  {the  Bloodwort  Family)  is  composed  of 
perennial  herbs,  with  fibrous  roots,  equitant  or  ensiform  leaves  ; 
which,  with  the  stems  and  flowers,  are  commonly  densely  clothed 
with  woolly  hairs  or  scurf.  Perianth  with  the  tube  either  nearly 
free  from,  or  commonly  adherent  to,  the  three-celled  ovary  ;  the 
limb  six-cleft,  regular.  Stamens  six,  or  only  three,  with  introrse 
anthers.  Style  single,  the  stigmas  standing  over  the  dissepiments 
of  the  ovary.  Embryo  in  cartilaginous  albumen.  —  Ex.  Lachnan- 
thes  (Red-Root),  Lophiola. 

41* 


486 


ENDOGENOUS    OR   MONOCOTYLEDONOUS   PLANTS. 


912.  Ord.  Amaryllidaceffi  {the  Amaryllis  Family).  Bulbous  plants 
(sometimes  with  fibrous  roots),  bearing  showy  flowers  mostly  on 
scapes.  Perianth  regular,  or  nearly  so ;  the  tube  adherent  to  the 
ovary,  and  often  produced  above  it,  six-parted.  Stamens  six,  dis- 
tinct, with  introrse  anthers.  Stigma  undivided  or  three-lobed. 
Fruit  a  three-celled  capsule  or  berry.  Seeds  with  fleshy  albumen. 
—  Ex.  Amaryllis,  Narcissus,  Crinum,  &c.  The  bulbs  acrid,  emet- 
ic, &c.  :  those  of  Hsemanthus  (with  whose  juice  the  Hottentots 
poison  their  arrows)  are  extremely  venomous.  The  fermented 
juice  of  Agave  is  the  intoxicating  Pulque  of  the  Mexicans. 

913.  Ord.  IridaceSB  {the  Iris  Family).  Perennial  herbs;  the 
flower-stems  springing  from  bulbs,  corms,  or  rhizomas,  rarely  with 
fibrous  roots,  mostly  with  equitant  leaves.  Flowers  regular  or 
irregular,  showy,  often  springing  from  a  spathe.  Perianth  with 
the  tube  adherent  to  the  three-celled  ovary,  and  usually  elongated 


above  it ;  the  limb  six-parted,  in  two  series.     Stamens  three,  dis- 


FIG.  1102.  Iris  crislala.  1103.  The  summit  of  the  style,  petaloid  stigmas,  and  stamens. 
1104.  Vertical  section  of  the  ovary  (the  equitant  leaves  cut  away)  and  long  tube  of  the  peri- 
anth. 1105.  Cross-section  of  the  pod.  1107.  Seed.  1106.  Enlarged  section  of  the  same,  show- 
ing the  embryo,  &c. 


ENDOGENOUS    OR    MONOCOTYLEDONOUS    PLANTS.  487 

tinct  or  monadelphous  ;  the  anthers  extrorse  !  Stigmas  three,  di- 
lated or  petaloid  !  Seeds  with  hard  albumen.  —  Ex.  Iris,  Crocus. 
The  rootstocks,  corms,  &c.,  contain  starch,  with  some  volatile 
acrid  matter.  Orris-root  is  the  dried  rhizoma  of  Iris  florentina,  of 
Southern  Europe.  Saffron  is  the  dried  orange  stigmas  of  Crocus 
sativus. 

914.  Ord.  DioscoreaceSB  {the  Yam  Family)  consists  of  a  few  twin- 
ing plants,  with  large  tuberous  roots  or  knotted  rootstocks  ;  distin- 
guished by  their  ribbed  and  netted-veined  leaves,  with  distinct  peti- 
oles, and  by  their  inconspicuous  dioecious  flowers.  Perianth  in 
thci  pistillate  flowers  adherent  to  the  ovary  ;  the  limb  six-cleft  in 
two  series.  Stamens  six.  Ovary  three-celled,  with  only  one  or 
two  ovules  in  each  cell :  styles  nearly  distinct.  Fruit  often  a  three- 
winged  capsule.  Albumen  cartilaginous.  —  Ex.  Dioscorea.  The 
tubers  of  one  or  more  species,  filled  with  starch  and  mucilage  (but 
more  or  less  acrid  until  cooked),  are  Yams,  an  important  article  of 
food  in  tropical  countries. 

915.  Ord.  SmilaceSB  {the  Smilax  Family).  Herbs  or  shrubby 
plants,  often  climbing,  with  the  veins  or  veinlets  of  the  leaves 
reticulated.  Flowers  perfect  or  dioecious.  Perianth  six-parted  or 
double,  the  three  sepals  green,  and  the  three  petals  colored.  Sta- 
mens six  :  anthers  introrse.  Cells  of  the  ovary  and  distinct  styles 
or  stigmas  three.  Berry  few-  or  many-seeded.  Albumen  hard. 
—  Ex.  Smilax  (Greenbrier,  Catbrier,  &c.).  Sarsaparilla  of  the 
shops  consists  of  the  roots  of  numerous  species  of  Smilax,  chiefly 
of  tropical  America.     Trillium  is  the  type  of  the  suborder  Trilli- 

ACE^. 

916.  Ord.  LiliaceSB  {the  Lily  Family).  Herbs,  with  the  flower- 
stems  springing  from  bulbs,  tubers,  or  with  fibrous  or  fascicled  roots. 
Leaves  simple,  sheathing  or  clasping  at  the  base.  Flowers  regu- 
lar, perfect.  Perianth  colored,  mostly  of  six  parts,  or  six-cleft. 
Stamens  six :  anthers  introrse.  Ovary  free,  three-celled ;  the 
styles  united  :  stigma  often  three-lobed.  Fruit  capsular  or  fleshy, 
with  several  or  numerous  seeds  in  each  cell.  Albumen  fleshy.  — 
Ex.  This  large  and  widely  diffused  order  comprises  a  great  varie- 
ty of  forms :  the  Lily  and  Tulip  represent  one  division  ;  the  Poli- 
anthes  (Tuberose),  a  second ;  the  Aloe  and  Yucca,  a  third ;  the 
Hyacinth,  the  Onion,  &c.  (Allium),  the  Asphodel,  Asparagus,  &c., 
a  fourth.  Acrid  and  often  bitter  principles  prevail  in  the  order, 
and  are  most  concentrated  in  the  bulbs,  &c.,  which  abound  in 


488 


ENDOGENOUS    OR   MONOCOTYLEDONOUS    PLANTS. 


Starchy  or  mucilaginous  matter,  and  are  often  edible  when  cooked. 
Squills  are  the  bulbs  of  Scilla  maritima  of  the  South  of  Europe. 
Aloes  is  yielded  by  the  succulent  leaves  of  species  of  Aloe.  The 
original  Dragon's-blood  was  derived  from  the  juice  of  the  famous 
Dragon-tree  (Dracaena  Draco)  of  the  East. 


917.  Ord.  PontederiaceSB  (the  Pickerel-weed  Family)  comprises  a 
few  aquatic  plants,  with  the  flowers,  either  solitary  or  spicate,  aris- 
ing from  a  spathe  or  from  a  fissure  of  the  petiole ;  the  six-cleft 
perianth  persistent  and  withering,  often  adherent  to  the  base  of  the 
three-celled  ovary ;  the  stamens  three,  and  inserted  on  the  throat 
of  the  perianth,  or  six,  and  unequal  in  situation.  Ovules  numer- 
ous ;  but  the  fruit  often  one-celled  and  one-seeded.  —  Ex.  Ponte- 
deria  (Pickerel-weed),  Heteranthera,  &c. 

918.  Ord.  Melanthacese  (the  ColcMcum  Family).  Herbs,  with 
bulbs,  corms,  or  fasciculated  roots.  Perianth  regular,  in  a  double 
series ;  the  sepals  and  petals  either  distinct,  or  united  below  into  a 
tube.     Stamens  six;   the  anthers  extrorse  (except  in  Tofieldia). 


FIG.  1108.    Erylhronium  Americanum  (Dog-tooth  Violet,  Adder's-tongue).     1109.  Perianth 
laid  open,  with  the  stamens.     1110.  The  pistil.     1111.  Cross-section  of  the  capsule. 


ENDOGENOUS    OR    MONOCOTYLEDONOUS    PLANTS. 


489 


Ovary  free,  three-celled,  several  seeded  :    styles  distinct.     Albu- 
men fleshy.     The  true  Melanthacese,  or 

919.  Sllbord.  MelanthieSB  have  a  mostly  septicidal  capsule  and  a 
marcescent  or  persistent  perianth.  —  Ex.  Colchicum  has  a  peri- 
anth with  a  long  tube,  arising  from  a  subterranean  ovary  ;  it  is  also 
remarkable  for  flowering  in  the  autumn,  when  it  is  leafless,  ripen- 
ing its  fruit  and  producing  its  leaves  the  following  spring.  In 
most  of  the  order,  the  leaves  of  the  perianth  are  uncombined ;  as 
in  Veratrum  (White  Hellebore),  Helonias,  &c.  Acrid  and  drastic 
poisonous  plants,  with  more  or  less  narcotic  qualities ;  chiefly  due 
to  a  peculiar  alkaloid  principle,  named  Veratria,  which  is  largely 
extracted  from  the  seeds  of  Sabadilla,  or  Cebadilla ;  the  produce 
of  Schcenocaulon  officinale,  &;c.,  of  the  Mexican  Andes. 


920.  Subord,  UvuIarieaB  {the  Bellwort  Family)  has  a  few-seeded 
loculicidal  capsule  or  berry,  more  or  less  united  styles,  and  a  de- 
ciduous perianth  ;  the  stems  from  rootstocks.  —  Ex,  Uvularia. 

921.  Ord.  JuncaceSB  {the  Rush  Family).  Herbaceous,  mostly 
grass-like  plants,  often  leafless :  the  small  glumaceous  flowers  in 


FIG.  1112.  Colchicum  autumnale ;  a  flowering  plant.  1113.  Perianth  laid  open.  1114.  Pia- 
til,  with  the  long  distinct  styles.  1115.  Leafy  stem  and  fruit  (capsule  opening  by  septicidal 
dehiscence).  1116.  Capsule  divided  transversely.  1117.  Section  of  a  seed,  and  a  separate  em- 
bryo. 


490  ENDOGENOUS    OR   M0N0C0TYLED0N0X7S    PLANTS. 

clusters,  cymes,  or  heads.  Perianth  mostly  dry,  greenish  or 
brownish,  of  six  leaves  (sepals  and  petals)  in  two  series.  Stamens 
six,  or  three.  Ovary  free,  three-celled,  or  one-celled  from  the 
placentae  not  reaching  the  axis ;  their  styles  united  into  one :  stig- 
mas three.  Capsule  three-valved,  few-  or  many-seeded.  Albu- 
men fleshy.  —  Ex.  Juncus  (Rush). 

922.  Ord.  Commelynacea;  (the  Spiderwort  Family),  with  usually 
sheathing  leaves  ;  distinguished  from  other  Endogens  (except  Alis- 
macese  and  Trillium)  by  the  manifest  distinction  between  the  calyx 
and  corolla ;  the  former  of  three  herbaceous  sepals  ;  the  latter  of 
as  many  delicate  colored  petals.  Stamens  six,  or  fewer :  anthers 
with  two  separated  cells  :  filaments  often  clothed  with  jointed 
hairs,  hypogynous.  Ovary  two-  or  three-celled  ;  the  styles  united 
into  one.  Capsule  few-seeded,  loculicidal.  Seeds  orthotropous. 
Embryo  small,  pulley-shaped,  partly  sunk  in  the  apex  of  the  albu- 
men. —  Ex.  Commelyna,  Tradescantia  (Spiderwort).  Mucilagi- 
nous plants. 

923.  Ord.  Xyridaceae.  Swampy,- rush-like  plants;  with  ensiform, 
grassy  or  filiform  radical  leaves,  sheathing  the  base  of  a  simple 
scape,  which  bears  a  head  of  flowers  at  the  apex,  imbricated  with 
bracts.  Calyx  of  three  glumaceous  sepals,  caducous.  Petals 
three,  with  claws,  more  or  less  united  into  a  monopetalous  tube. 
Stamens  six,  inserted  on  the  corolla ;  three  of  them  bearing  ex- 
trorse  anthers,  the  others  mere  sterile  filaments.  Ovary  one-celled, 
with  three  parietal  placentae,  or  three-celled :  styles  partly  united  : 
stigmas  lobed.  Capsule  many-seeded.  Seeds  orthotropous,  albu- 
minous. —  Ex.  Xyris  (Yellow-eyed  Grass). 

924.  Ord.  EriocaulonaceSB  (the  Pipewort  Family).  Swampy  or 
aquatic  herbs,  with  much  the  aspect  and  structure  of  the  preced- 
ing; their  leaves  cellular  or  fleshy ;  their  minute  flowers  (monoe- 
cious or  dioecious)  crowded,  along  with  scales  or  hairs,  into  a  very 
compact  head :  the  corolla  less  petaloid  than  in  Xyridaceae ;  the 
six  stamens  often  all  perfect ;  the  ovules  and  seeds  solitary  in  each 
cell.  —  Ex.  Eriocaulon. 

925.  Ord.  CyperaceSB  (the  Sedge  Family).  Stems  (culms)  usually 
solid,  csespitose.  Sheaths  of  the  leaves  closed.  Flowers  one  in 
the  axil  of  each  glumaceous  bract.  Perianth  none,  or  of  a  few 
bristles.  Stamens  mostly  three,  hypogynous.  Styles  two  or  three, 
more  or  less  united.  Fruit  an  achenium.  Embryo  small,  at  the 
extremity  of  the  seed  next  the  hilum.  —  Ex.  Cyperus,  Scirpus, 


ENDOGENOUS  OR  MONOCOTYLEDONOUS  PLANTS. 


491 


Carex.      Sedge-Grasses.  —  The  papyrus  of  the    Egyptians   was 
made  from  the  stems  of  Cyperus  Papyrus. 


926.  Ord.  Graillinea3  (the  Grass  Famihj).  Stems  (culms)  cylindri- 
cal, mostly  hollow,  and  closed  at  the  nodes.  Sheaths  of  the  leaves 
split  or  open.  Flowers  in  little  spikelets,  consisting  of  two-ranked 
imbricated  bracts ;  of  which  the  exterior  are  called  glumes,  and 
the  two  that  immediately  inclose  each  flower,  palece.  Perianth 
none,  or  in  the  form  of  very  small  and  membranous  hypogynous 
scales,  from  one  to  three  in  number,  distinct  or  united  (termed 
sqiiamulcB,  squamellce,  or  lodiculce).  Stamens  commonly  three : 
anthers  versatile.      Styles  or   stigmas  two  ;    the  latter   feathery. 


FIG.  1118.  Scirpus  triqueter,  with  its  cluster  of  spikelets.  1119.  A  separate  flower,  en- 
larged, showing  its  rudimentary  perianth  of  a  few  denticulate  bristles,  its  three  stamens,  and 
pistil  with  a  three-cleft  style :  a,  section  of  the  seed,  showing  the  minute  embryo.  1120.  Carex 
Careyana,  reduced  in  size  (flowers  monoecious,  the  two  kinds  in  different  spikes).  1121.  Stem, 
with  the  staminate  and  upper  pistillate  spike,  of  the  size  of  nature.  1122.  A  scale  of  the  stam- 
inate  spike,  with  the  flower  (consisting  merely  of  three  stamens)  in  its  axil.  1123.  Magnified 
pistillate  flower,  with  its  scale  or  bract :  tlie  ovary  inclosed  in  a  kind  of  sac  (_perigynium), 
formed  by  the  union  of  two  br2ictlet3.  1124.  Cross-section  of  the  perigynium;  with  the  pistil, 
p,  removed.    1125.  Vertical  section  of  the  achenium,  showing  the  seed. 


492 


ENDOGENOUS  OR  MONOCOTYLEDONOUS  PLANTS. 


Fruit  a  caryopsis  (607).  Embryo  situated  on  the  outside  of  the 
farinaceous  albumen,  next  the  hilum.  —  Ex.  Agrostis,  Phleum, 
Poa,  Festuca,  which  are  the  principal  meadow  and  pasture  grasses: 
Oryza  (Rice),  Zea  (Maize),  Milium  (Millet),  Avena  (the  Oat), 
Triticum  (Wheat),  Secale  (Rye),  Hordeum  (Barley),  are  the  chief 
cereal  plants,  cultivated  for  their  farinaceous  seeds.  This  univer- 
sally diffused  order,  one  of  the  largest  of  the  vegetable  kingdom, 
is  doubtless  the  most  important ;  the  floury  albumen  of  the  seeds, 
and  the  nutritious  herbage,  constituting  the  chief  support  of  man 
and  the  herbivorous  animals.  No  unwholesome  properties  are 
known  in  the  family,  except  in  the  seeds  of  Lolium  temulentum, 
which  are  deleterious.  The  Ergot,  or  Spurred  Rye,  forms  no  real 
exception  to  this  rule,  as  it  is  caused  by  parasitic  fungus.  —  The 


stems  of  grasses  frequently  contain  sugar  in  considerable  quantity ; 


FIG.  1126.  One-flowered  spikelet  or  locus'a  of  Alopecurus,  with  the  glumes  separated. 
1127.  Same,  with  the  glumes  removed:  an  atcn  on  the  back  of  the  outer  palea.  1128.  One- 
flowered  spikelet  of  an  Agrostis.  1129.  Pistil  of  a  Grass,  showing  the  two  feathery  stigmas, 
and  the  two  hypogynous  scales  or  squamulae  (representing  the  perianth).  1130.  Two-flowered 
spikelet  of  an  Avena;  with  the  glumes  spreading.  1131.  One  of  the  flowers  with  its  paleae; 
the  exterior  pointed,  with  two  bristles  or  cusps  at  the  apex,  and  with  a  bent  awn  on  the  back. 
1132.  Many-flowered  spikelet  of  Glyceria  fluitans.  1133.  An  enlarged  separate  flower  of  the 
same,  seen  from  within,  showing  the  inner  palea,  &c.  1134.  The  fruit  (caryopsis)  of  the 
Wheat,  with  an  oblique  section  through  the  integuments  of  the  embryo,  which  is  exterior  to 
the  albumen.  1135.  Detached  magnified  embryo:  a,  the  imperfect  lower  cotyledon;  6,  the 
large  cotyledon;  c,  the  plumule;  d,  the  radicle.  1136.  The  caryopsis  of  Hordeum  (Barley). 
11-37.  A  cross-section.  1138.  A  vertical  section,  showing  the  external  embryo  at  the  base. 
1139.  Magnified  detached  embryo,  with  its  broad  cotyledon  and  the  plumule.  1140,  More 
magnified  vertical  section  of  the  same :  a,  the  plumule ;  b,  the  radicle. 


CRYPTOGAMOUS    OR   FLOWERLESS    PLANTS. 


493 


especially  in  the  few  instances  where  it  is  solid,  as  in  the  Maize, 
and  more  largely  in  the  Sugar-Cane  (Saccharum  officinarum), 
which  affords  the  principal  supply  of  this  article. 


Series  II.     Cryptogamous  or  Flowerless  Plants. 

Plants  destitute  of  proper  flowers  (stamens  and  pistils),  and 
propagated  by  spores  instead  of  seeds  (101, 109). 

Class  III.     Acrogenous  Plants. 

Vegetables  with  a  distinct  axis,  growing  from  the  apex,  with  no 
provision  for  subsequent  increase  in  diameter  (containing  woody 
and  vascular  tissue),  and  usually  with  distinct  foliage  (108). 

927.  Ord.  EquisetaceSB  {the  Horse-tail  Family).  Leafless  plants  ; 
with  striated,  jointed,  simple  or  n^  lui 
branched  stems  (containing  ducts 
and  some  spiral  vessels),  which 
are  hollow  and  closed  at  the 
joints  ;  each  joint  terminating  in  a 
toothed  sheath,  which  surrounds 
the  base  of  the  one  above  it.  In- 
florescence consisting  of  peltate 
scales  crowded  in  a  terminal 
spike,  or  kind  of  strobile :  each 
with  several  thecce  attached  to  its 
lower  surface,  longitudinally  de- 
hiscent. Spores  numerous,  with 
four  elastic  club-shaped  bodies 
(of  unknown  use,  called  elaters) 
wrapped  around  them.  —  Ex. 
Equisetum.  The  epidermis  of 
Equisetum  hyemale  (Scouring 
Rush)  contains  so  much  silex 
that  it  is  used  for  polishing. 

928.  Ord.  Filices  (Ferns).    Leafy  plants;  with  the  leaves (/row^Zs) 

FIG.  114L  Summit  of  the  stem  of  Equiaetum  sylvaticum.  1142.  Part  of  the  axis  of  the 
cone  of  fructification,  with  some  of  the  fruit- bearing  organs,  shown  magnified  in  Fig.  1143. 
1144.  A  separate  theea,  more  magnified.    1145,  1146.  Spores  with  elaters,  still  more  magnified. 

42 


1146 


494 


CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS. 


spirally  rolled  up  or  circinate  in  vernation  (except  in  one  subor- 
der), usually  rising  from  prostrate  or  subterranean  rootstocks, 
sometimes  from  an  erect  arborescent  trunk  (Fig.  94),  and  bearing, 
on  the  veins  of  their  lower  surface,  or  along  the  margins,  the  sim- 
ple fructification,  which  consists  of  one-celled  spore-cases  [theccB 
or  sporangia)^  opening  in  various  ways,  and  discharging  the  nu- 
merous minute  spores.  The  stalk  or  petiole  of  the  frond  is  termed 
a  stipe.  —  There  are  three  principal  suborders,  viz. :  — 


929.  Subord.  PolypodineSB.     Sporangia  collected  in  dots,  lines,  or 
variously  shaped  clusters  {sori  or  fruit-dots)  on  the  back  or  mar- 


FIG.  1147.  Asplenium  (Camptosorus)  rhizophyllum  (Walking  Fern) ;  the  fronds  rooting,  as 
they  frequently  do,  at  the  apex;  the  sori  occupying  the  reticulated  veins  on  the  back.  1148. 
Division  (pinnula)  of  a  frond  of  Aspidium  (Nephrodium)  Goldianum ;  the  roundish  sori  attached 
to  the  simple  veins,  and  covered  with  an  indusium,  which  is  fastened  in  the  centre,  and  opens 
all  around  the  margin.  1149.  Magnified  sporangium  of  this  division  of  Ferns,  with  its  stalk, 
and  elastric  ring  partly  surrounding  it;  which,  tending  to  straighten  itself  when  dry,  tears 
open  the  sporangium,  shedding  the  minute  spores  (1150).  1151.  Schizaea  pusilla  of  about  the 
natural  size,  with  simple  and  slender  radical  leaves;  the  contracted  fertile  frond  pinnate. 
1152.  A  division  (pinna)  of  the  fertile  frond,  magnified,  showing  the  sessile  sporangia  occupy- 
ing.its  lower  surface.  1153.  One  of  the  sporangia  more  magnified  ;  they  have  no  proper  ring, 
and  open  by  a  longitudinal  cleft.  1154.  Ophioglossum  vulgatum  (Adder-tongue);  the  sporan- 
gia forming  a  two-ranked  spike  on  a  transformed  and  contracted  frond  :  a,  portion  of  the  spike 
enlarged,  showing  the  coriaceous  sporangia^  destitute  of  a  ring  and  opening  transversely. 


CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS.  495 

gins  of  the  frond  or  its  divisions,  stalked,  cellular-reticulated,  the 
stalk  running  into  a  vertical  incomplete  ring,  which  by  straighten- 
ing at  maturity  ruptures  the  sporangium  transversely  on  the  inner 
side,  discharging  the  spores.  Fruit-dots  often  covered,  at  least 
when  young,  by  a  membrane  called  the  involucre^  or  indusium. 

930.  Subord.  Osmundineae,  Sporangia  variously  collected,  desti- 
tute of  any  proper  ring,  cellular-reticulated,  opening  lengthwise  by 
a  regular  slit. 

931.  Subord.  Opllioglosseae.  Sporangia  spiked,  closely  sessile, 
naked,  coriaceous  and  opaque,  not  reticulated,  destitute  of  a  ring, 
opening  by  a  transverse  slit  into  two  valves,  discharging  the  very 
copious  spores  which  appear  like  floury  dust.  Fronds  straight, 
never  rolled  up  (circinate)  in  the  bud ! 

932.  Ord.  Lycopodiaceae  {the  Club-Moss  Family).  Plants  with 
creeping  or  erect  leafy  stems,  mostly  branching;  the  crowded 
leaves  lanceolate  or  subulate,  one-nerved.  Thecse  sessile  in  the 
axils  of  the  leaves,  sometimes  all  collected  at  the  summit  under- 
leaves  which  are  changed  into  bracts  and  crowded  into  a  kind  of 
ament,  one-celled,  or  rarely  two-  to  three-celled,  dehiscent,  con- 
taining either  minute  grains,  appearing  like  fine  powder,  or  a  few 
rather  large  sporules ;  both  kinds  often  found  in  the  same  plant. 

—  Ex.  Lycopodium  (Club- Moss,  Ground  Pine,  Fig.  89-93),  Psi- 
lotum.  —  Appended  to  this  family,  rather  than  to  the  next,  is  the 

933.  Subord.  {soctineaB  {the,  Qmllwort  Family),  consisting  of  a 
few  acaulescent  submersed  aquatics,  with  sporangia  in  the  axils 
and  immersed  in  the  inflated  base  of  the  grassy  stalk-like  leaves. 

—  Ex.  Isoetes. 

934.  Ord.  Ilydropterides.  Aquatic  cryptogamous  plants  of  diverse 
habit,  with  the  fructification  borne  at  the  bases  of  the  leaves,  or  on 
submerged  branches,  consisting  of  two  sorts  of  organs,  of  dubious 
nature,  contained  in  indehiscent  or  irregularly  bursting  involucres 
(sporocarps) :  —  comprising  the 

935.  Subord.  Marsilese  {the  Pepperwort  Family) ;  with  creeping 
stems;  the  leaves  long-stalked,  circinate  in  vernation;  —  of  four 
obcordate  leaflets  in  Marsilea,  or  filiform  and  destitute  of  leaflets 
in  Pilularia  (the  Pillwort). 

936.  Subord.  Salviniese ;  which  are  free  floating  plants,  with  al- 
ternate and  sometimes  imbricated  sessile  leaves ;  the  fructifica- 
tion borne  on  the  stem  or  branches  underneath.  —  Ex.  Salvinia, 
Azolla. 


496 


CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS. 


Class  IV.     Anophytes. 

Vegetables  composed  of  parenchyma  alone,  with  acrogenous 
growth,  usually  with  distinct  foliage,  sometimes  the  stem  and  foli- 
age confluent  into  a  frond  (105,  Fig.  87,  88). 

937.  Ord.  Musci  (Mosses).  Low,  tufted  plants,  always  with  a 
stem  and  distinct  (sessile)  leaves,  producing  spore-cases  which 
mostly  open  by  a  terminal  lid,  and  contain  simple  spores  alone. 
Reproductive  organs  of  two  kinds  :  —  1.  The  sterile  flower,  consist- 
ing of  numerous  (4-20)  minute  cylindrical  sacs  (antheridia) 
which  discharge  from  their  apex  a  mucous  fluid  filled  with  oval 
particles,  and  then  perish.  2.  The  fertile  flower,  composed  of 
numerous  (4-20)  flask-like  bodies  {pistillidia) ,  each  having  a 
membranous  covering  (caJyptra),  terminated  by  a  long  cylindri- 


pf    (^ 


1165  1163 


cal  funnel-mouthed  tube  (style).     The  ripened  pistillidium   (sel- 


FIG.  1155.  Mnium  cuspidatum.  1156.  The  calyptra  detached  from  the  theca.  1157.  Mag- 
nified theca,  from  which  the  lid  or  operculum,  1158,  has  been  removed,  showing  the  peristome. 
1159.  A  portion  of  the  annuhis,  magnified.  1160.  A  portion  of  the  outer  and  inner  peristome, 
highly  magnified.  1161.  The  so-called  flowers  in  a  young  state,  consisting  of  the  young  thecae 
$  ,  and  the  antheridia  ^  ,  with  some  cellular  jointed  threads  intermixed ;  the  involucral 
leaves  cut  away.  1162.  One  of  the  antheridia  more  magnified  (with  the  accompanying  cellular 
threads),  opening  at  the  apex,  and  discharging  the  fo villa.  1163.  Simple  peristome  of  Splach- 
num;  the  teeth  united  in  pairs.  1164.  Double  peristome  of  Hypnum;  the  exterior  spreading. 
1165.  Physcomitrium  (Gymnostomum)  pyriforme.  1166.  Its  calyptra,  detached  from  1167,  the 
theca.    1168.  The  lid  removed  from  the  orifice,  which  is  destitute  of  a  peristome. 


CRYPTOGAMOUS    OR   FLOWERLESS    PLANTS.  497 

dom  more  than  one  in  a  flower  maturing)  becomes  the  capsule^ 
which  is  rarely  indehiscent  or  splitting  by  four  longitudinal  slits, 
but  usually  opens  by  a  lid  [operculum) :  beneath  the  lid  and  aris- 
ing from  the  mouth  of  the  capsule  are  commonly  either  one  or 
two  rows  of  rigid  processes  (collectively  the  peristome)^  which  are 
always  some  multiple  of  four :  those  of  the  outer  row  are  called 
teeth^  of  the  inner,  cilia.  An  elastic  ring  of  cells  (annulus)  lies 
between  the  rim  of  the  capsule  and  operculum.  The  powdery 
particles  filling  the  capsule  are  spores.  The  thread-like  stalk  (ped- 
icel) supporting  the  capsule  is  inserted  into  the  elongated  torus 
{vaginula)  of  the  flower.  The  pedicel  continued  through  the  cap- 
sule forms  the  columella :  enlarged  under  the  capsule  it  sometimes 
forms  an  apophysis.  The  calyptra  separating  early  at  its  base  is 
carried  up  on  the  apex  of  the  capsule ;  if  it  splits  on  one  side  it  is 
hood -shaped  or  cuculliform^  if  not,  it  is  mitre-shaped  or  mitriform. 
Intermixed  with  the  reproductive  organs  are  jointed  filaments  {par- 
aphyses).  The  leaves  next  the  antheridia  are  called  perigonial 
leaves,  those  around  the  pistillidia  or  pedicel  the  perichcBtial  leaves. 

938.  Ord.  HepaticSB  (Liverworts).  Frondose  or  Moss-like  plants, 
of  a  loose  cellular  texture,  usually  procumbent  and  emitting  root- 
lets from  beneath ;  the  calyptra  not  separating  from  the  base,  but 
usually  rupturing  at  the  apex ;  the  capsule  not  opening  by  a  lid, 
containing  spores  usually  mixed  with  elaters  (which  are  thin, 
thread-like  cells,  containing  one  or  two  spiral  fibres,  uncoiling  elas- 
tically  at  maturity).  Vegetation  sometimes  frondose,  i.  e.  the 
stem  and  leaves  confluent  into  an  expanded  leaf-like  mass  ;  some- 
times foliaceous,  when  the  leaves  are  distinct  from  the  stem,  as  in 
true  Mosses,  entire  or  cleft,  two-ranked,  and  often  with  an  imper- 
fect or  rudimentary  row  (amphigastria)  on  the  under  side  of  the 
stem.  Reproductive  organs  of  two  kinds,  viz.  antheridia  and 
pistillidia,  much  as  in  Mosses  (937),  variously  situated.  The 
matured  pistillidium  forms  the  capsule,  which  is  either  sessile  or 
borne  on  a  long  cellular  pedicel,  and  dehiscent  by  irregular  open- 
ings, by  teeth  at  its  apex,  or  lengthwise  by  two  or  four  valves.  A 
columella  is  rarely  present.  The  perianth  is  a  tubular  organ  in- 
closing the  calyptra,  which  directly  includes  the  pistillidium.  Sur- 
rounding the  perianth  are  involucral  leaves  of  particular  forms. 
The  antheridia  in  the  foliaceous  species  are  situated  in  the  axils  of 
perigonial  leaves. 

939.  Subord.  RicciaceSB  are  chiefly  floating  plants,  rooting  from 
42* 


CRYPTOGAMOUS    OR   FLOWERLESS   PLANTS. 

beneath,  with  the  fructification  immersed  In  the  frond,  the  sporan- 
gium bursting  irregularly.    No  involucre  nor  elaters.  —  Ex.  Riccia. 

11S9  iiro  im 


940.  Subord.  Anthoceroteae.  Terrestrial  frondose  annuals,  with 
the  fruit  protruded  from  the  upper  surface  of  the  frond.  Perianth 
none.  Capsule  pod-like,  one-  to  two-valved,  with  a  free  central 
columella.     Elaters  none  or  imperfect. 

941.  Subord.  MarchantiaceSB  {true  Liverworts).  Frondose  and 
terrestrial  perennials,  growing  in  wet  places,  with  the  fertile  recep- 
tacle raised  on  a  peduncle,  capitate  or  radiate,  bearing  pendent  ca- 
lyptrate  capsules  from  the  under  side,  which  open  variously,  not 
four-valved.     Elaters  with  two  spiral  fibres. 

942.  Subord.  JungermanniaceBB.  Frondose  or  mostly  foliaceous 
plants ;  with  the  sporangium  dehiscent  into  four  valves,  and  the 
spores  mixed  with  elaters  (Fig.  84-86). 


Class  V.     Thallophytes. 

Vegetables  composed  of  parenchyma  alone,  of  congeries  of  cells, 
or  even  of  separate  cells,  often  vaguely  combined  in  a  thallus, 
never  exhibiting  a  marked  distinction  into  root,  stem,  and  foliage, 
or  into  axis  and  leaves  (94-104,  106).  Fructification  of  the 
most  simple  kinds.     (Spores  often  termed  sporules,  or  sporidia.) 

943.  Ord.  Licbenes  {Lichens)  form  the  highest  grade  of  this  lower 
series.     They  consist  of  flat  expansions,  which  are  rather  crusta- 


FIG.  1169,  1170.  Riccia  natang,  about  the  natural  size.  1171.  Magnified  section  through 
the  thickness  of  the  frond,  showing  the  immersed  sporangia ;  one  of  which  has  burst  through 
and  left  aa  effete  cavity.  1172.  Magnified  vertical  section  of  one  of  the  sporangia,  with  the 
contained  spores.  1173.  Sporangium  torn  away  from  the  base,  and  a  quaternary  group  of 
spores,  united  and  separated. 


CRYPTOGAMOUS    OR   FLOWERLESS    PLANTS. 


499 


ceous  than  foliaceous.  Their  structure  is,  as  it  were,  anticipated 
in  Riccia,  above  mentioned  (Fig.  1170).  They  are  by  no  means 
aquatic,  however,  but  grow  on  the  ground,  on  the  bark  of  trees,  or 
on  the  surface  of  exposed  rocks,  to  which  they  cling  by  their  lower 
surface,  often  with  the  greatest  tenacity,  while  by  the  upper  they 
draw  their  nourishment  directly  from  the  air  (Fig.  1174).  The 
fructification  is  in  cups^  or  shields  (apothecia,  Fig.  1176),  resting 
on  the  surface  of  the  thallus,  or  more  or  less  immersed  in  its  sub- 
stance (Fig.  1178),  or  else  in  pulverulent  spots  scattered  over  the 
surface.  A  magnified  section  through  an  apothecium  (Fig.  1176) 
brings  to  view  a  stratum  of  elongated  sacs  {asci)^  with  filaments 


intermixed,  as  seen  detached  and  highly  magnified  at  Fig.  1177. 


FIG.  1174.  A  stone  upon  which  several  Lichens  are  growing,  such  as  (passing  from  left  to 
right)  Parmelia  conspersa,  Sticta  miniala,  Lecidea  geographica  (so  called  from  its  patches  re- 
sembling the  outline  of  islands,  &c.,  on  maps),  &c.,  &c.  1175.  Piece  of  the  thallus  of  Parme- 
lia conspersa,  with  a  section  through  an  apothecium.  1176.  Section  of  a  smaller  apothecium, 
more  magnified.  1177.  Two  asci  and  their  contained  spores,  with  the  accompanying  filaments, 
highly  magnified.  1178.  Section  of  a  piece  of  the  thallus  of  Sticta  miniata,  showing  the  im- 
mersed apothecia.  1179.  Cladonia  coccinea,  bearing  its  fructification  in  rounded  red  masses 
on  the  edges  of  a  raised  cup. 


500  CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS. 

Each  ascus^  or  sac,  contains  a  few  spores,  which  divide  into  two, 
but  generally  remain  coherent.  The  vegetation  of  some  Lichens 
rises  info  a  kind  of  axis,  as  in  the  Cladonia  coccinea,  which 
abounds  on  old  logs  (Fig.  1179);  or  in  Cladonia  rangiferina,  the 
Reindeer  Moss  ;  also  in  Usnea,  where  it  forms  long,  gray  tufts, 
hanging  from  the  boughs  of  old  trees  in  our  Northern  forests. 

944.  Ord.  Fungi  {Mushrooms^  Moulds^  SfC.)  are  parasitic  (137) 
Flowerless  plants,  either  in  a  strict  sense,  as  living  upon  and  draw- 
ing their  nourishment  from  living,  though  more  commonly  lan- 
guishing, plants  and  animals,  or  else  as  appropriating  the  organized 
matter  of  dead  and  decaying  animal  and  vegetable  bodies.  Hence 
they  fulfil  an  office  in  the  economy  of  creation  analogous  to  that 
of  the  infusory  animalcules.  Those  Fungi  which  produce  Rust, 
Smut,  Mildew,  &c.,  ar6  of  the  first  kind ;  those  which  produce 
Dry-rot,  &c.,  hold  a  somewhat  intermediate  place ;  and  Mush- 
rooms, Puff-balls,  &c.,  are  examples  of  the  second.  Fungi  are 
consequently  not  only  destitute  of  any  thing  like  foliage,  but  also 
of  the  green  naatter,  or  chlorophyll,  which  appears  to  be  essential 
to  the  formation  of  organic  out  of  inorganic  matter  (87,  135,  344). 
A  full  account  of  the  diversified  modifications  of  structure  that 
Fungi  display,  and  of  the  remarkable  points  in  their  economy, 
would  require  a  volume.  We  will  notice  three  sorts  only,  which 
may  represent  the  highest,  and  nearly  the  lowest,  forms  of  this 
vast  order  or  class  of  plants.  They  all  begin  (in  germination  or 
by  offsets)  with  the  production  of  copious  filamentous  threads,  or 
series  of  attenuated  cells,  appearing  like  the  roots  of  the  fungus 
that  arises  from  them  (Fig.  1179,  1181),  and  to  a  certain  extent 
performing  the  functions  of  roots  :  this  is  called  the  mycelium^  and 
is  the  true  vegetation  of  Fungi.  The  subsequent  developments 
properly  belong  to  the  fructification,  or  are  analogous  to  tubers, 
rhizomas,  &c.  In  one  part  of  the  order,  the  masses  that  arise,  of 
various  definite  shapes,  and  often  attaining  a  large  size,  contain  in 
their  interior  a  multitude  of  asci  (Fig.  1180),  inclosing  simple  or 
double  sporules,  just  as  in  Lichens.  The  esculent  Morel  has  this 
kind  of  fructification  ;  as  well  as  the  less  conspicuous  Spheeria 
(Fig.  1179),  which  is  in  other  respects  of  a  lower  grade.  The 
Agarics,  like  the  Edible  Mushroom  (Fig.  1181),  present  a  differ- 
ent type.  Rounded  tubercles  appear  on  the  mycelium ;  some  of 
these  rapidly  enlarge,  burst  an  outer  covering  which  is  left  at  the 
base  (the  volva^  or  wrapper)^  and  protrude  a  thick  stalk  (stipes). 


CRYPTOGAMOUS    OR    FLOWERLESS   PLANTS. 


501 


bearing  at  its  summit  a  rounded  body  that  soon  expands  into  the 
pileus,  or  cap.     The  lamellcB,  or  gills  {hymenium),  that  occupy  its 


lower  surface,  consist  of  parallel  plates  (Fig.  1182),  which  bear 
naked  sporules  over  their  whole  surface.  A  careful  inspection 
with  the  microscope  shows  that  these  sporules  are  grouped  in 
fours ;  and  the  view  of  a  section  of  one  of  the  gills  shows  their 
true  origin  (Fig.  1183).  Certain  of  the  cells  (basidia),  one  of 
which  is  shown  more  magnified  at  Fig.  1184,  produce  four  small 
cells  at  their  free  summit,  apparently  by  gemmation  and  constric- 
tion :  these  are  the  sporules.  It  is  maintained  that  the  larger  in- 
termingled cells,  (of  which  one  is  shown  at  Fig.  1183,  a,)  filled 
with  an  attenuated  form  of  matter,  are  the  analogues  of  stamens. 
The  lowest  Fungi  produce  from  their  mycelium  only  simple  or 
branching  series  of  cells  (Fig.  74-76).  The  mycelium  itself 
either  ramifies  through  decaying  organized  matter,  as  the  Moulds, 

FIG.  1179;  Sphaeria  rosella.  1 180.  Asci  from  its  interior,  containing  sporules,  highly  mag- 
nified. 1181.  Agaricus  campestris,  the  Edible  Mushroom,  in  its  various  stages.  1182.  Section 
through  the  pileus,  to  display  the  gills.  1183,  A  small  piece  of  a  slice  through  the  thickness 
of  one  of  the  gills,  magnified;  showing  the  spores  borne  on  the  summit  of  salient  cells  of  both 
surfaces.    1184.  One  of  the  sporule-bearing  eel's,  with  some  subjacent  tissue,  more  magnified. 


502 


CRYPTOGAMOUS    OR   FLOWERLESS  PLANTS. 


&c. ;  or  else,  like  the  Blight  and  Rust  in  grain,  and  the  Muscar- 
dine  so  destructive  to  silkworms,  it  attacks  and  spreads  throughout 
living  tissues,  often  producing  great  havoc  before  its  fructification 
is  revealed  at  the  surface.     Sometimes  the 
last  cells  of  the  stalks  swell  into  a  vesicle, 
in  which  the  minute  sporules  are  formed ; 
as  in  Fig.  74.      Sometimes  the  branching 
stalks  bear  single  sporules,  like  a  bunch  of 
grapes  (Fig.  76),  or  long  series  of  cells,  or 
sporules,  in  rows,  like  the  beads  of  a  neck- 
lace (Fig.  75),  which,  falling  in  pieces,  are 
the  rudiments  of  new  plants. 

945.  Ord.  CharaceaB.  The  Chara  Family 
consists  of  a  few  aquatic  plants,  which  have 
all  the  simplicity  of  the  lower  Algge  in  their 
cellular  structure,  being  composed  of  sim- 
ple tubular  cells  placed  end  to  end,  and  of- 
ten with  a  set  of  smaller  tubes  applied  to  the 
surface  of  the  main  one  (Fig.  1186).  Hence 
they  have  been  placed  among  Algae.  But 
their  fructification  is  of  a  higher  order.  It 
consists  of  two  kinds  of  bodies  (both  shown 
in  Fig.  1186),  of  which  the  smaller  (and 
lower)  is  probably  a  mass  of  antheridia  use  ii85 
of  curious  structure,  while  the  upper  and  larger  is  a  sporocarp, 
formed  of  a  budding  cluster  of  leaves  wrapped  around  a  nucleus, 
which  is  a  spore  or  sporangium.  The  order  should  have  been  in- 
troduced between  the  Equisetaceae  (to  which  the  verticillate  branch- 
es show  some  analogy)  and  the  Hydropterides,  which  they  some- 
what resemble  in  fructification.  They  are,  of  all  plants,  those  in 
which  the  rotary  movement  of  the  contents  of  the  cells  (36,  which 
has  been  called  Cydosis)  may  be  most  readily  observed. 

946.  Ord.  Alga;  {Seaweeds).  This  vast  order,  or  rather  class, 
consists  of  aquatic  plants ;  for  the  most  part  strictly  so,  but  some 
grow  in  humid  terrestrial  situations.  The  highest  forms  are  the 
proper  Seaweeds  ( Wrack^  Tang,  Dulse,  Tangle,  &c.)  ;  "  some  of 
which  have  stems  exceeding  in  length  (although  not  in  diameter) 


FIG.  1185.  Branch  of  the  common  Chara,  nearly  the  natural  size.  1186.  A  portion  magni- 
fied, showing  the  lateral  tubes  inclosing  a  large  central  one  (a  portion  more  magnified  at  1187) ; 
also  a  spore,  invested  by  a  set  of  tubes  twisted  spirally  around  it ;  and  with  an  antheridium 
borne  at  its  base. 


CRYPTOGAMOUS    OR    FLOWERLESS   PLANTS.  503 

the  trunks  of  the  tallest  forest-trees,  while  others  have  leaves 
(fronds)  which  rival  in  expansion  those  of  the  Palm."  "  Others 
again  are  so  minute  as  to  be  wholly  invisible,  except  in  masses,  to 
the  naked  eye,  and  require  the  highest  powers  of  our  microscopes 
to  ascertain  their  form  and  structure."  Some  have  the  distinction 
of  stems  and  fronds  ;  others  show  simple  or  branching  solid  stems 
only ;  and  others  flat  foliaceous  expansions  alone  (Fig.  82),  either 
green,  olive,  or  rose-red  in  hue.  From  these  we  descend  by  suc- 
cessive gradations  to  simple  or  branching  series  of  cells  placed  end 
to  end,  such  as  the  green  Confervas  of  our  pools,  and  many  marine 
forms  (Fig.  81) :  we  meet  with  congeries  of  such  cells  capable  of 
spontaneous  disarticulation,  each  joint  of  which  becomes  a  new 
plant,  so  that  the  organs  of  vegetation  and  of  fructification  become 
at  length  perfectly  identical,  both  reduced  to  mere  cells ;  and 
finally,  as  the  last  and  lowest  term  of  possible  vegetation,  we  have 
the  plant  reduced  to  a  single  cell,  giving  rise  to  new  ones  in  its 
interior,  each  of  which  becomes  an  independent  plant  (94-99). 

947.  The  fructification  of  Algae  exhibits  four  principal  varieties. 
In  the  great  division  of  olive-brown  or  olive-green  proper  Sea- 
weeds, the  MELANosPERMEiE  of  Harvoy,  the  fructification  forms  tu- 
bercles immersed  in  the  tissue  of  the  summit  of  the  branches  of 
the  frond  (Fig.  1188-  1191),  which  are  filled  with  a  mass  of  sim- 
ple spores  with  filaments  intermixed  (1191),  invested  by  a  proper 
membranous  coat,  and  finally  escaping  from  the  frond  by  a  minute 
orifice.  The  beautiful  red-colored  Seaweeds,  or  RnoDOSPERMEiE, 
exhibit  two  kinds  of  spores  ;  one  large,  simple,  superficial,  and  re- 
sembling those  above  described,  except  that  they  have  no  proper 
integument ;  the  others,  dispersed  through  the  interior  of  the  frond, 
are  formed  fou?  together  in  a  mother  cell.  The  bright  green  se- 
ries, or  Chlorosperme^,  have  the  whole  green  contents  of  certain 
cells,  or  of  some  part  of  the  cell,  (as  in  Vaucheria,  Fig.  71,  72, 
467,  and  in  Conferva  vesicata.  Fig.  474,  &c.,)  condensed  into  a 
spore,  in  some  of  the  ways  already  described  (95-101),  or  else 
they  result  from  the  conjugation  of  two  cells  (102,  Fig.  78-81). 
This  conjugation  occurs  throughout  in  the 

948.  Subord.  Desmidiese,  which  are  microscopic  and  infusory  green 
Algse  of  single  cells  (Fig  77-80)  often  of  crystal-like  forms,  in- 
vested with  mucus,  and  belonging  to  fresh  water.  They  multiply 
largely  by  division,  but  propagate  only  by  conjugation.  Many  of 
them  have  long  been  claimed  for  the  animal  kingdom,  or  esteemed 


504 


CRYPTOGAMOUS    OR    FLOWERLESS    PLANTS. 


of  ambiguous  nature,  on  account  of  the  free  movements  they  ex- 
hibit (661) ;  but  these  are  nearly  as  well  marked  in  Oscillaria,  &c. 
(Fig.  66).  More  ambiguous  still,  and  on  the  lowest  confines  of 
the  vegetable  kingdom,  are  those  minute  vegetables,  as  they 
doubtless  are,  which  constitute  the 


1193       1199 


949.  Subord.  Diatomaceae.  These  essentially  differ  from  the  last 
in  the  brown  instead  of  green  color  of  their  contents,  in  the  sili- 
ceous and  durable  nature  of  their  cell-wall,  and  in  being  natives  of 
salt,  instead  of  fresh  water.  Their  movements,  as  they  break  up 
from  their  connections,  are  still  more  vivid  and  varied.  Some  are 
fixed  (Fig.  1207)  ;  others  are  free.  Some  are  extremely  minute  ; 
others  consist  of  clusters  of  cells  of  considerable  size. 


FIG.  1188.  Summit  of  the  frond  of  Fucus  vesiculosua.  1189.  Section  of  one  of  the  recepta- 
cles. 1190.  One  of  the  contained  globules.  1191.  Spores  and  jointed  filaments  of  which  the 
globules  are  composed.  1192.  Delesseria  Le  Prieurii.  1193.  The  sterile  plant.  1194.  Magni- 
fied portion  of  the  fertile  frond.  1195.  Portion  of  the  same,  more  magnified,  showing  its  tissue 
from  the  midrib  to  the  margin.  A.  Theca,  opened,  with  the  spores.  11S6.  Portion  of  the 
network  of  Hydrodyction  utriculatum.  1197.  A  magnified  joint,  filled  with  the  green  matter 
which  developes  into  a  new  plant.  119S.  Single  filament  of  Tyndaridea  cruciata,  showing  the 
star-shaped  bodies,  enveloped  in  mucus.  1199.  Two  filaments  of  the  same  united  side  by  side. 
1200.  Vaucheria  geminata,  in  fruit.  B.  Vesicular  receptacles,  enlarged.  —  The  remaining  fig- 
ures represent  some  of  the  ambiguous  Diatomaceae.  1201.  Gonium  glaucum,  of  Ehrenberg, 
who  thinks  it  a  congeries  of  animalcules ;  while  Meyen  has  described  it  as  an  Alga.  C.  Closte- 
rium  Lunula ;  usually  filled  with  floating  green  globules :  a,  the  perfect  vegetable ;  b,  the  same, 
separating  into  two  by  spontaneous  division  ;  c,  an  individual  resulting  from  this  spontaneous 
division,  developing  a  second  ;  d,  two  individuals  conjugately  united ;  the  green  matter  all 
collected  in  the  uniting  globule.  1202.  Euastrum  Pecten,  and  1203,  E.  Crux-Melitensis.  1204. 
A  Diatoma,  breaking  up  into  separate  individuals.  1205.  A  Fragillaria.  1206.  MeriJion  circu- 
late, front  and  side  views.     1207.  Echinella  flabellata;  perhaps  a  group  of  animalcules. 


APPENDIX, 


Of  the  Signs  and  Abbreviations  employed  in  Botanical  Writings. 

LiNNiEus  adopted  the  following  signs  for  designating  the  duration  of  a 
plant,  namely  :  — 
^  An  annual  plant. 
$  A  biennial  plant. 
1|.  A  perennial  herb. 
\^  A  shrub  or  tree. 

Among  the  signs  recently  introduced,  the  following  have  come  into 
general  use :  — 

O  A  monocarpic  plant,  whether  annual  or  biennial. 

(J)  An  annual  plant. 

(g)  A  biennial  plant. 

1].  A  perennial  herb. 

1^  A  plant  with  a  woody  stem. 

$  A  staminate  flower,  or  plant. 

$   A  pistillate  flower,  or  plant. 

5   A  perfect  flower,  or  a  plant  bearing  perfect  flowers. 
!    The  exclamation  point  is  employed  as  the  counterpart  of  the  note 
of  interrogation.     When  it  follows  the  name  of  an  author  appended 
to  the  name  of  a  plant,  it  imports  that  an  authentic  specimen  of  the 
plant  in  question,  under  this  name,  has  been  examined  by  the  writer  : 
when  it  is  appended  to  a  locality,  it  signifies  that  the  writer  has 
seen  or  collected  specimens  of  the  plant  from  that  locality,  &c. 
?   The  note  of  interrogation  is  similarly  employed  in  case  of  doubt  or 
uncertainty ;  and  is  afiixed  either  to  a  generic  or  specific  name,  or 
to  that  of  an  author  or  locality  cited. 
*   As  used  by  De  Candolle,  indicates  that  a  good  description  is  found 
at  the  reference  to  which  it  is  appended.     It  is  not  in  common  use. 
43 


506  APPENDIX. 

Those  abbreviations  of  the  names  of  organs  which  are  commonly  em- 
ployed, such  as  Cal.  for  calyx,  Cor.  for  corolla,  Fl.  for  flower,  Fr.  for 
fruit.  Gen.  for  genus,  Hab.  for  habitat.  Herb,  for  herbarium,  Hort.  for 
garden,  Mus.  for  Museum,  Ord.  for  order,  Rad.  (Radix)  for  root,  Syn.  for 
synonymy,  Sf.  or  Spec,  for  species,  Var.  for  variety,  &c.,  scarcely  re- 
quire explanation. 

V.  sp.  denotes,  in  general  terms,  that  the  writer  has  seen  the  plant  under 

consideration. 
V.  s.  c.  (  Vidi  siccam  cultam),  that  a  dried  specimen  of  a  cultivated  plant 

has  been  examined. 
V.  s.  s.  {Vidi  siccam  spontaneam),  that  a    dried  specimen  of  the  wild 

plant  has  been  examined. 
V.  V.  c.  ( Vidi  vivam  cultam) ,  that  the  living  cultivated  plant  has  been 
under  examination. 
,,  V.  v.  s.  (  Vidi  vivam  spontaneam),  that  the  wild  plant  has  been  examined 
in  a  living  state. 
The  names  of  authors,  when  of  more  than  one  syllable,  are  commonly 
abridged  by  writing  the  first  syllable,  and  the  first  letter  or  the  first  con- 
sonant of  the  second.    Thus,  imn.,  or  Z.,  is  the  customary  abbreviation 
for  Linnaeus  ;  Juss.  for  Jussieu ;    Willd.  for  Willdenow  ;  Muhl.  for  Muh- 
lenberg ;  Michx.  for  Michaux  ;  Rich,  for  Richard;  De  Cand.,  or  DC, 
for  De  Candolle ;    Hook,  for  Hooker ;    End!,  for  Endlicher  ;    Lindl.  for 
Lindley,  &c. 


Of  Collecting  and  Preserving  Plants. 

1.  The  botanist's  collection  of  specimens  of  plants,  preserved  by  drying 
under  pressure  between  folds  of  paper,  is  termed  a  Hortus  Siccus,  or 
commonly  an  Herbarium. 

2.  A  complete  specimen  consists  of  one  or  more  shoots,  bearing  the 
leaves,  flowers,  and  fruit ;  and,  in  case  of  herbaceous  plants,  a  portion  of 
the  root  is  also  desirable. 

3.  Fruits  and  seeds  which  are  too  large  to  accompany  the  dried  speci- 
mens, or  which  would  be  injured  by  compression,  with  sections  of  wood, 
&c.,  should  be  separately  preserved  in  cabinets. 

4.  Specimens  for  the  herbarium  should  be  gathered,  if  possible,  in  a  dry 
day ;  and  carried  either  in  a  close  tin  box,  as  is  the  common  practice,  or 
in  a  strong  portfolio,  containing  a  quire  or  more  of  firm  paper,  with  a  few 
loose  sheets  of  blotting-paper  to  receive  delicate  plants.  They  are  to 
be  dried,  under  strong  pressure,  (but  without  crushing  the  parts,)  be- 
tween dryers  composed  of  six  to  ten  thicknesses  of  bibulous  paper  ;  which 
should  be  changed  daily,  or  even  more  frequently,  until  all  the  moisture  is 
extr'acled  from  the  plants;  —  a  period  which  varies  in  different  species,  and 
with  the  season,  from  two  or  three  days  to  a  week.     All  delicate  speci- 


APPENDIX.  507 

mens  should  be  laid  in  folded  sheets  of  thin  and  smooth  bibulous  paper 
(such  as  tea-paper),  and  such  sheets,  filled  with  the  freshly  gathered 
specimens,  are  to  be  placed  between  the  dryers,  and  so  transferred  entire, 
day  after  day,  into  new  dryers,  without  being  disturbed,  until  perfectly 
dry.  This  preserves  all  delicate  flowers  better  than  the  ordinary  mode  of 
shifting  the  papers  which  are  in  immediate  contact  with  the  specimens, 
and  also  saves  much  time  usually  lost  in  transferring  numerous  small 
specimens,  one  by  one,  into  dry  paper,  often  to  the  great  injury  of  the  deli- 
cate corolla,  &c. 

5.  The  dried  specimens,  properly  ticketed  with  the  name,  locality,  &c., 
and  arranged  under  their  respective  genera  and  orders,  are  preserved  in 
the  herbarium,  either  in  separate  double  sheets,  or  with  each  species  at- 
tached by  glue  or  otherwise  to  a  half-sheet  of  strong  white  paper,  with 
the  name  written  on  one  corner.  These  are  collected  in  folios,  or  else  lie 
flat  (as  is  the  best  mode)  in  parcels  of  convenient  size,  received  into 
compartments  of  a  cabinet,  with  close  doors,  and  kept  in  a  perfectly  dry 
place. 

6.  Thg  seeds  of  plants  intended  for  cultivation,  which  are  to  be  trans- 
ported to  a  distance  before  being  committed  to  the  earth,  should  first  be 
dried  in  the  sun,  wrapped  in  coarse  paper,  and  preserved  in  a  dry  state. 
They  should  not  be  packed  in  close  boxes,  at  least  so  long  as  there  is 
danger  of  the  retention  of  moisture. 

7.  Roots,  shrubs,  &c.,  designed  for  cultivation,  should  be  taken  from 
the  ground  at  the  close  of  their  annual  vegetation,  or  early  in  the  spring 
before  growth  recommences,  and  packed  in  successive  layers  of  slightly 
damp  (but  not  wet)  Peat-moss  (Sphagnum).  Succulent  plants,  however, 
such  as  Cacti,  may  be  packed  in  dry  sand. 

8.  Plants  in  a  growing  state  can  only  be  safely  transported  to  a  consid- 
erable distance,  especially  by  sea,  in  the  closely  glazed  cases  invented  by 
Mr.  Ward  ;  *  where  they  are  provided  with  the  requisite  moisture,  while 
they  are  fully  exposed  to  the  light. 

*  On  the  Growth  of  Plants  in  Closely  Glazed  Cases,  by.  N.  B.  Ward, 
F.  L.  S.,  London,  1842. 


INDEX 


AND     GENERAL     GLOSSARY     OF     BOTANICAL     TERMS. 


Abbreviations,  505 

Abietineae,  476. 

Abortion,  246, 263. 

Abortive,  291. 

Abruptly  pinnate,  168. 

Acanthaceae,  444. 

Acanthus  Family,  444. 

Acaulescent;  apparently  stemless. 

Accessory  buds,  100. 

Accrescent,  289. 

Accumbent,  335. 

Ace  race  ae,  404. 

Acerose  ;  needle-shaped,  as  the  leaves 
of  Juniper. 

Achenium,  326. 

Achlarnydeous,  264. 

Acrogenous  plants,  74,  493. 

Acrogens,  74. 

Aculeate;  armed  with  prickles. 

Aculeolate ;  armed  with  little  prickles. 

Acuminate,  168. 

Acute,  167. 

Adder's-tongue  Family,  495. 
Adnate,  259,  292. 
Adnation,  246,  258. 
Adventitious  buds,  100. 
Adventitious  roots,  87. 
Aerial  roots,  87. 
-Estivation,  278. 
Air  cells,  54. 
Air  passages,  54. 
Air  plants,  89. 
Alae,  261. 
Alate,  172. 
Albumen,  319,  331. 
Alburnum,  125. 
Algae,  361,  502. 
Alismacese,  482. 


Alkaloids,  61. 

Almond  Family,  412. 

Alsineae,  392. 

Alternate,  140,  241. 

Alternate  leaves,  142. 

Alveolate ;  honey-combed. 

Amarantaceae,  462. 

Amaranth  Family,  462. 

Amaryllidaceae,  486. 

Amaryllis  Family,  486. 

Ament,  218. 

Amentaceous  trees,  219. 

Amnios,  315. 

Amphigastria,  497. 

Amphitropous,  312. 

Amplexicaul ;  clasping. 

Amygdaleae,  412. 

Amyridaceae,  403. 

Anacardiaceae,  403. 

Anastomosing,  161. 

Anatropous,  311. 
Ancipital ;  two-edged. 
Androecium,  228,  289. 
Androgynous,  277. 
Angiospermia,  360. 
Angiospermous,  364. 
Angiospermous  plants,  371. 
Angular  divergence,  143. 
Anisomerous,  270. 
Annual  layers,  113. 
Annual  roots,  85. 
Annular  ducts,  50. 
Annulus,  497. 
Anonaceae,  378. 
Anophytes,  364,  496. 
Anterior,  243,  298. 
Anther,  228,  291. 
Antheridia,  497. 


INDEX   AND   GLOSSARY. 


509 


Anthesis,  281. 

Antliocarpoiis  fruits,  328. 

Anlhoceroteae,  498. 

Anthophore,  277. 

Apetalae,  264,  367. 

Apetalous,  264. 

Apetalous  plants,  457. 

Apocarpous,  300. 

Apocynaceae,  455. 

Apophysis,  497. 

Apoihecia,  500. 

Appressed ;  lying  flat  against. 

Aquifoliaceae,  439. 

Araceae,  480. 

Arachnoid  ;  with  cobwebby  hairs. 

Araliaceae,  425. 

Areolate ;  divided  into  angular  spaces 

Aril,  331. 

Arillus,331. 

Aristate;  with  an  awn. 

Aristolochiaceae,  459. 

Arrangement  of  leaves,  140. 

Arrow-headed,  164. 

Arrowroot  Family,  485. 

Articulated,  168. 

Articulation,  176. 

Artificial  system,  356. 

Artocarpeae,  474. 

Arum  Family,   480. 

Ascending,  309. 

Ascending  axis,  93. 

Ascending  radicle,  335. 

Ascidia,  173. 

AsclepiadacesB,  455. 

Ascus,  500. 

Assimilation,  21,  194. 

Assurgent ;  obliquely  ascending. 

Atropous,  311. 

Augmentation,  245. 

Aurantiaceffi,  397. 

Auriculate ;    eared,  with    two   rouud 
lobes  at  the  base. 

Automatic  movements,  345. 

Awn  ;  a  bristle-like  appendage. 

Axillary,  225. 

Axillary  buds,  98. 

Axis  of  inflorescence,  216. 

Baccate ;  berry-like. 

Balsam  Family,  400. 

Balsamifluae,  474. 

Balsaminaceae,  400. 

Balsams,  200. 

Banana  Family,  485. 

Banded  ducts,  49. 

Banner,  261. 
,    Barberry  Family,  380. 

Bark,  118,  127. 

Basidia,  502. 

Bassorin,  59. 

Bast  tissue,  46. 

Bearded  ;  with  a  tufl;  of  hairs. 

Bellwort  Family,  436. 

43* 


Bent,  151. 
Berberidaceae,  380. 
Berry,  327. 
Betulaceae,  473. 
Biennial  roots,  85. 
Bifid,  166. 

Bifoliate  ;  with  two  leaflets. 
Bifurcate ;  two-forked. 
Bignoniaceae,  444. 
Bignonia  Family,  444. 
Bilabiate,  261,288. 
Bilocular,  302. 
Binate,  170. 
Bipinnate,  170. 
Bipinnatifid,  167. 
Birch  Family,  472. 
Birthwort  Family,  459. 
Bisexual,  264. 
Biternate,  170. 
Bixaceae,  390. 
Bladder-nut  Family,  407. 
Bladderwort  Family,  443. 
Blade,  157,  286. 

Bloodwort  Family,  485. 

Bloom,  156. 

Bolivariae,  457.' 

Borage  Family,  448. 

Boraginaceae,  448. 

Bothrenchyma,  48. 

Brachiate;    with  opposite    spreading 
branches. 

Bracteoles,  221. 

Bractlets,  221. 

Bracts,  151,  216. 

Branches,  98. 

Branchlets,  99. 

Bread-fruit  Family,  474. 

Breathing-pores,  157. 

Bristles,  55. 

Bromeliaceae,  485. 

Broom-Rape  Family,  443 

Buckbean  Family,  454. 

Buckthorn  Family,  406. 

Buckwheat  Family,  462. 

Budding,  32. 

Buds,  95. 

Bulb,  110. 

Bulblets,  llO. 

Burmanniaceae,  483. 

Burseraceae,  403. 

Butomaceae,  483. 

Byttneriaceas,  395. 

Cabombaceae,  381. 

Cactaceae,  418. 

Cactus  Family,  418. 

Caducous ;  falling  off*  early. 

Caesalpinese,  410. 

Caespitose  ;  forming  a  tuft. 

Calcarate,  288. 

Callitrichaceae,  468. 

CalycanthaceaB,  414. 

Calyculate  ;  with  an  outer  calyx. 


510 


INDEX   AND   GLOSSARY 


Calyptra,  497. 
Calyx,  227,  263,  285. 
Cambium,  121. 
Cambium  layer,  121. 
Campanulaceae,  436. 
Campanula  Family,  436. 
Campanulate,  287. 
Campy lotropous,  311. 
Canaliculate  ;  channelled. 
Canescent ;  whitened  with  close  hairs. 
Cannabineae,  475. 
Cannaceae,  485.  / 

Caoutchouc,  57. 
Cap,  501. 

Caper  Family,  386. 
Capillary ;  hair-like. 
Capitulum,  219. 
Capparidacea;,  386. 
Caprifoliacese,  428. 
Capsule,  328,  497. 
Carina,  261. 
Carinate ;  keeled. 
Carpel,  300. 

Carpet-weed  Family,  393. 
Carpidium,  300. 
Carpophore,  277,  327.' 
Caruncle,  331. 
Caryophyllacese,  391. 
Caryophyllaceous,  287. 
Caryopsis,  327. 
Cashew  Family,  403. 
Catkin,  218. 
Cat-tail  Family,  481. 
Caudate ;  with  an  appendage  or  pro- 
longation like  a  tail. 
Caudex,  104. 
Cauline,  150. 
Cedrelaceae,  398. 
Celastraceae,  406. 
Cells,  24,  228. 
Cellular,  152. 
Cellular  envelope,  119. 
Cellular  plants,  73,  364. 
Cellular  structure,  23. 
Cellular  tissue,  24. 
Cellulose,  28,  196. 
Centrifugal,  223,  226,  335. 
Centripetal,  218,  226,  335. 
Ceratophyllaceae,  468. 
Chaff,  220,  433. 
Chalaza,  311. 
Characese,  502. 
Characters,  354. 
Chara  Family,  502. 
Chenopodiaceae,  461. 
Chickweed  Family,  392. 
Chlorophyll,  60,  194. 
Chlorospermeae,  503. 
Chorisis,  246,  249. 
Chlorosis,  235. 
Chromule,  61. 
ChrysobalanesB,  412. 


Cilia,  497. 

Ciliate  ;  the  margin  fringed  with  hairs. 

Cinchonese,  430. 

Cinenchyma,  52. 

Circinate,  225. 

Circinnate,  151. 

Circulation  in  cells,  33. 

Circumcissile,  324. 

Circumscription  ;  the  general  outline. 

Cirrhose  ;  furnished  with  tendrils. 

Cistacese,  389. 

Classes,  354. 

Classification,  15,  349. 

Clavate ;  club-shaped. 

Claw,  278,  286. 

Cleft,  166,  257. 

Club-Moss  Family, 495. 

Clusiaceae,  390. 

Coalescence,  246,  256. 

Cocci,  323. 

Cocoa-plum  Family,  412. 

Cohesion,  258. 

Coils  in  cells,  42. 

Colchicum  Family,  488. 

Collateral  chorisis,  250. 

Collective  fruits,  328. 

Colored,  263. 

Columella,  324,  497. 

Column,  484. 

Coma,  330. 

Commelynaceae,  490. 

Commissure,  327. 

Complete  flower,  227,339. 

Compositae,  432. 

Composite  Family,  432. 

Compound  corymb,  221. 

Compound  flowers,  220. 

Compound  leaves,  168. 

Compound  organs,  64. 

Compound  pistil,  301. 

Compound  raceme,  221. 

Compound  spike,  221. 

Compound  umbel,  221. 

Compressed ;  flattened  laterally. 

Concentric  layers,  113, 

Conduplicate,  284. 

Cone,  329. 

Conferruminate,  336. 

Coniferae,  476. 

Conjugate ;  in  pairs. 

Conjugation,  69. 

Connate,  259. 

Connate-perfoliate,  174. 

Connective,  291. 

Connectivum,  291. 

Connivent;  converging. 

Constituents  of  plants,  183. 

Contorted,  282. 

Convolute,  151,  281,  282. 

Convolvulacese,  451. 

Convolvulus  Family,  451. 

Cordate,  164. 


OF    BOTANICAL    TERMS. 


511 


Coriaceous ;  leathery  in  texture. 

Corky  envelope,  119. 

Conn,  109. 

Cormophytes,  73,  365. 

Cormus,  109. 

Cornaceae,  425. 

Cornel  Family,  425. 

Corneous,  332. 

Corolla,  228,  286. 

Corrugate,  279. 

Corymb,  217. 

Corymbose ;  in  corymbs. 

Costate  ;  ribbed. 

Cotyledons,  77, 151,  317. 

CranesbiU  Family,  399. 

Crassulaceae,  421. 

Cremocarp,  326. 

Crenate,  166. 

Crowberry  Family,  470. 

CrowfootFamily,  376. 

Crown,  289. 

Cruciate,  287. 

Cruciferse,  385. 

Cruciform,  287. 

Crude  sap,  56,  194. 

Crumpled,  279. 

Cryptogamia,  358. 

Cryptogamous  plants,  74,  339,  493. 

Crystals,  62. 

Cucullate;  hooded. 

Cuculliform,  497. 

Cucurbitaceae,  420. 

Culm,  104,  491. 

Cuneate  ;  see  Cuneiform. 

Cuneiform,  163. 

Cup,  278. 

Cupressinese,  476. 

CupulifersB,  471. 

Curvinerved,  165. 

Cuscutineae,  453. 

Cuspidate ;    tipped  with  a  sharp  and 

strong  point. 
Custard-Apple  Family,  378. 
Cuticle,  156. 
CycadacesB,  477. 
Cycas  Family,  477. 
Cycle,  143. 
Cyclosis,  503. 
Cyme,  223. 
Cymules,  223. 
Cyperaceae,  490. 
Cypress  Family,  476. 
Cytoblast,  28. 
Decagynia,  360. 
Decagynous,  297. 
Decandria,  357. 
Decandrous,  290. 
Deciduous,  175,289. 
Peclined,  291. 
Decompound,  170. 
Decumbent ;  lying  on  the  ground. 
Decurrent,  172. 


Dedoublement,  253. 

Deduplication,  246, 249. 

Definite,  309. 

Definite  inflorescence,  222. 

Dehiscence, 293,  323. 

Dehiscent,  323. 

Deliquescent  stems,  101. 

Deltoid  ;  with  a  triangular  outline. 

Demersed  ;  under  water. 

Dentate,  166. 

Depressed  ;  flattened  vertically. 

Descending  axis,  80. 

Descending  radicle,  335. 

Descriptive  Botany,  15. 

Desmidiese,  503. 

Determinate  inflorescence,  222. 

Development  of  cells,  26. 

Development  of  the  embryo,  77. 

Development  of  leaves,  160. 

Dextrine,  59,  197. 

Diadelphia,  358. 

Diadelphous,  257,  290. 

Diandria,  357. 

Diandrous,  290. 

Diapensiaceae,  450. 

Diatomaceae,  504. 

Dichondreae,  452. 

Dichotomous  ;  successively  forked. 

Diclinous,  264. 

Dicoccous,  323. 

Dicotyledonous,  334. 

Dicotyledonous  plants,  114,  371. 

Dicotyledonous  stem,  114. 

Didynamia,  357. 

Didynamous,  271,  290. 

Diftuse ;  loosely  spreading. 

Digynia,  360. 

Digynous,  297. 

Dimerous,  240. 

Dimidiate,  293. 

Dicecia,  358,  361. 

Dioecious,  266. 

Dioscoreaceae,  487. 

Diphyllous,  285. 

Diplostemons,  267. 

Dipsaceae,  432. 

Dipterocarpeap,  396. 

Discoid,  433. 

Disepalous,  285. 

Disk,  259. 

Dissepiment,  301. 

Distichous,  142. 

Distinct,  258,  278. 

Divaricate;  very  widely  spreading. 

Divided,  166. 

Dodecagynia,  360. 

Dodecandria,  357. 

Dodecandrous,  290. 

Dogbane  Family,  455. 

Dorsal  suture,  298,  305. 

Dotted  ducts,  39,  48. 

Double  flowers,  234. 


512 


INDEX   AND   GLOSSARY 


Droseraceae,  388. 

Drupaceous,  326. 

Drupe,  325. 

Duck-weed  Family,  481. 

Ducts,  48. 

Duramen,  124. 

Duration  of  leaves,  175. 

Earthy  constituents,  189. 

Ebenaceaj,  439. 

Ebony  Family,  439. 

Echinate  ;  clothed  with  prickles. 

Elaborated  sap,  56. 

Elaters,  497. 

ElatinacesB,  391. 

Eleagnaceae,  464. 

Elliptical,  163. 

Elm  Family,  466. 

Emarginate,  168. 

Embryo,  77,  317,  333. 

Embryonal  vesicle,  316. 

Embryo-sac,  315. 

Emersed  ;  raised  out  of  water. 

EmpetraceoB,  470. 

Endocarp,  322,  325. 

Endogenous  plants,  477. 

Endogenous  structure,  114. 

Endogens,  114,  129. 

EndophlsBum,  119. 

Endopleura,  330. 

Endosmosis,  34. 

Endosperm,  331. 

Enneagynia,  360. 

Enneandria,  357. 

Enneandrous,  290. 

Entire,  165,  256,  286. 

EpacridacesB,  439. 

Epicarp,  322. 

Epidermal  system,  55. 

Epidermis,  55,  155. 
Epigynous,  259,  290. 

Epiphiaeum,  119. 

Epiphytes,  89. 

Episperm,  329. 

Equisetaceae,  493. 

Equitant,  152,  171. 

Erect,  3U9. 

Ericaceae,  436. 

Ericineae,  437. 

Erigoneae,  463. 

EriocaulonacesB,  490. 

Essential  oils,  57. 

Essential  organs,  228,  229. 

Euphorbiaceae,  469. 

Evening- Primrose  Family,  416. 

Evolution  of  heat,  212. 

Exalbuminous,  333. 

Exceiitric,  335. 

Excurrent  stems,  101. 

Exhalation,  179. 

Exocarp,  322,  325. 

Exogenous  plants,  371. 

Exogenous  stem,  114. 


Exogenous  structure,  114. 

Exogens,  114. 

Exosmosis,  34. 

Exserted,  291. 

Exstipulate,  175. 

Exterior,  227. 

Extine,  296. 

Extra-axillary,  225. 

Extrorse,  292. 

Falcate;     scythe-shaped,    somewhat 

bent  to  one  side. 
Falsely  ribbed,  167. 
Families,  353, 
Farina,  57. 
Farinaceous,  332. 
Fascicle,  224. 
Fascicled,  150. 
Fastigiate  ;  level-topped. 
Favose ;  deeply  pitted. 
Feather-veined,  162. 
Fecula,  57. 
Ferns,  493. 
Fertile,  264. 
Fertilization,  313. 
Fibrils,  82. 
Fibrous  roots,  85. 
Fibro- vascular  system,  54. 
Fibro-vascular  tissue,  54. 
Figwort  Family,  445. 
Filament,  228,  291. 
Filices,  361,493. 
Filiform  ;  thread-like. 
Filiformly  dissected,  165. 
Fimbriate  ;  fringed. 
Fir  Family,  476. 
Five-ranked,  143. 
Fixed  oils,  60. 
Flabelliform  ;  fan-shaped. 
Flax  Family,  398. 
Floral  envelopes,  227,  277. 
Floral  leaves,  151,  216. 
Floret ;  a  small  or  imperfect  flower. 
Flower,  227. 
Flowering,  209. 
Flowering  plants,  75,  371. 
Flowerless  plants,  74,  339, 493. 
Folded,  151. 
Foliaceous,  497. 
Follicle,  325. 
Food  of  plants,  181,  183. 
Foramen,  310. 
Forcing,  214.    > 
Formation  of  cells,  27. 
Forms  of  leaves,  160. 
Fovillae,  296. 
Free,  259. 

Frog's-bit  Family,  483. 
Frondose,497. 
Fronds,  493. 
Fruit,  320. 
Fugacious,  175. 
FumariaceaB,  385. 


OF    BOTANICAL    TERMS. 


513 


Fumitory  Family,  385. 

Fundamental  organs,  79. 

Fungi,  361,  500. 

Funiculus,  309,  330. 

Fusiform ;  spindle-shaped,  85. 

Galea,  288. 

Gamopetalae,  367. 

Gamopetalous,  256. 

Gamopetalous  plants,  426. 

Gamophyllous,  278. 

Gamosepalous,  256. 

Geminate  ;  in  pairs. 

Gemmation,  32. 

Genera,  352. 

Generic  character,  355. 

Gentianaceae,  454. 

Gentian  Family,  454. 

Genus,  352. 

Geraniaceae,  399. 

Germ  ;  the  growing  point  of  a  bud,  a 
rudiment. 

Germen ;  the  old  name  for  the  ovary. 

Germinal  vesicle,  317. 

Germination,  336. 

Gesneriaceae,  444. 

Gibbous  ;  enlarged  on  one  side. 

Gills,  501. 

Ginger  Family,  484. 

Glabrous;  smooth,  without  pubes- 
cence. 

Glands,  55,  267. 

Glandular;  furnished  with  glands. 

Glandular  hairs,  55. 

Glaucous ;  covered  with  a  grayish 
white  powder,  or  bloom,  that  rubs 
off. 

Glomerule,  224. 

Glossology,  15. 

Glurnaceous ;  glume-like. 

Glumes,  491. 

Gluten,  202. 

Gonophore,  277. 

Gooseberry  Family,  418. 

Goosefoot  Family,  461. 

Gourd  Family,  420. 

Gramineae,  491. 

Grass  Family,  491. 

Green  layer,  119. 

Grossulaceae,  418. 

Gutta  percha,  57. 

GuttifersB,  390. 

Gymnospermia,  360. 

Gymnospermous,  309,  364. 

Gymuospermous  plants,  476. 

Gynaecium,  228,  306. 

Gynandria,  358. 

Gynandrous,  290. 

Gynophore,277. 

Hasmodoraceae,  485. 

Hairs,  55. 

Halberd-shaped,  164. 

Half-equitant,  152. 


Halorageae,  417. 

Hamamelaceae,  423. 

Hastate,  164. 

Head,  218,  219. 

Heart-shaped,  164. 

Heart- wood,  124. 

Heath  Family,  436. 

Helicoid,  225. 

Helmet,  288. 

Hemicarp,  327. 

Hemp  Family,  475. 

Hepaticae,  497. 

Heptagynia,  360. 

Heptagynous,  297. 

Heptandria,  357. 

Heptandrous,  290. 

Herbs,  103. 

Hesperidium,  327. 

Heterogamous,  277,433. 

Heterotropous,  312. 

Hexagynia,  360. 

Hexagynous,  297. 

Hexandria,  357. 

Hexandrous,  290. 

Hexaphyllous,  285. 

Hexasepalous,  285. 

Ililum,  311,  330. 

Hippocastanaceae,  405. 

Hirsute  ;  clothed  with  coarse  spread- 
ing hairs. 

Hispid;  clothed  with  rigid  hairs  or 
bristles. 

Holly  Family,  439. 

Homogamous,  277, 433. 

Homologous,  230. 

Honeysuckle  Family,  428. 

Horizontal,  309. 

Hornwort  Family,  468.    • 

Horse-tail  Family,  493. 

Hybrids,  352. 

Hydrangeas,  423. 

Hydrangea  Family,  423. 

HydrocharidacetB,  483. 

Hydroleaceae,  450. 

Hydrophyllaceae,  449. 

Hydropterides,  495. 

Hymenium,  501. 

Hypericaceae,  390. 

Hypocrateriform,  288. 

Hypogasous,  338. 

Hypogynous,  259,  290. 

Icosandria,  357. 

Illecebreae,  392. 

Imbibition,  34. 

Imbricated,  152,  280. 

Imbricative,  279. 

Impari-pinnate,  169. 

Incised,  166. 

Incisions,  165. 

Included,  291. 

Incomplete,  263. 

Incumbent,  292,  335. 


514 


INDEX   AND   GLOSSARY 


Indefinite,  249, 309. 

Indefinite  inflorescence,  216. 

Indehiscent,  322. 

Indeterminate  inflorescence,  216. 

Indian-Cress  Family,  400. 

Indian-Pipe  Family,  438. 

Individual  plant,  64. 

Individuals,  20,  349. 

Induplicate,  152,  279. 

Indusium,  495. 

Inferior,  243,  260. 

Inferior  radicle,  335. 

Inflexed, 151. 

Inflorescence,  215. 

Infundibuliform,  287. 

Innate,  292. 

Inner  bark,  119. 

Inner  suture,  298. 

Inserted,  229. 

Insertion,  141,  259. 

Integuments  of  the  seed,  329. 

Intercellular  passages,  54. 

Intercellular  spaces,  24. 

Intercellular  system,  54. 

Interlaced  tissue,  52. 

Internal  glands,  54. 

In  tern  odes,  94. 

Interpetiolar,  175. 

Interruptedly  pinnate,  169. 

Intine,  296. 

Intrafoliaceous,  175. 

Introrse,  292. 

Inuline,  198. 

Involucel,  221. 

Involucellate  ;  with  an  involucel. 

Involucrate  ;  vv^ith  an  involucre. 

Involucre,  219,  495. 

Involute,  151,  284. 

Iridaceae,  486. 

Iris  Family,  486. 

Irregular,  260,  270. 

Irregularity,  246, 260. 

Isoetineae,  495. 

Isomeric,  198. 

Jasminaceae,  456. 

Jessamine  Family,  456. 

Juglandaceae,  471. 

Juncaceffi,  489. 

Juncagineas,  482. 

Jungermanniaceas,  498. 

Keel,  261. 

Kidney-shaped,  164. 

Knawel  Family,  393. 

Knotwort  Family,  392. 

Krameriacese,  409. 

Labeilum,  289. 

Labiata3,  447. 

Labiate,  288. 

Labiate  Family,  447. 

Labiatiflorte,  433. 

Laciniate  ;  cut  into  irregular  incisions. 

Lamellae,  501. 

Lamina,  152,  286. 


Lanate ;  woolly. 

Lanceolate,  163. 

Lateral,  298. 

Lateral  buds,  98. 

Laticiferous  tissue,  152. 

Lauracese,  463. 

Laurel  Family,  463. 

Leadwort  Family,  442. 

Leaflets,  168. 

Leafstalk,  152,  171. 

Legume,  325. 

Legumine,  202. 

LeguminosaB,  409. 

LemnacesB,  481. 

Lentibulaceae,  443. 

Lepidote,  55. 

Liber,  46, 119. 

Lichens,  499. 

Lid,  497. 

Life,  21. 

Lignine,  37,  199. 

Ligulate,  433. 

Ligule,  172. 

Liguliflorae,  433. 

Liliaceae,  487. 

Liliaceous,  287. 

Lily  Family,  487. 

Limb,  152,  286. 

Limnanthaccae,  401. 

Linaceae,  398. 

Linden  Family,  395. 

Linear,  163. 

Line  of  dehiscence,  292. 

Linnaean  system,  356. 

Liverworts,  497. 

Lizard-tail  Family,  467. 

Loasaceae,  419. 

Lobed,  166,  257. 

Lobeliaceae,  435. 

Lobelia  Family,  435. 

Lobes,  165,  286. 

Loculi,  302. 

Loculicidal,  324. 

Loganieae,  430. 

Loment,  325. 

Lomentaceous,  325. 

Longitudinal  system,  53, 113. 

Longitudinal  tissue,  48. 

Loosestrife  Family,  416. 

Loranthaceae,  466. 

Lunate ;  crescent-shaped. 

Lunulate  ;  diminutive  of  lunate. 

Lycopodiaceae,  495. 

Lyrate,  166. 

Lyrately  pinnate,  169. 

Lythraceaj,  416. 

Madder  Family,  429. 

Magnoliae,  377. 

Magnoliaceffi,  377. 

Magnolia  Family,  377. 

Mahogany  Family,  398. 

Mallow  Family,  394. 

MalpighiaceaB,  404. 


OF   BOTANICAL    TERMS. 


515 


Malvaceae,  394. 

Mangrove  Family,  416. 

Maple  Family,  404. 

Marcesent,  289. 

MarchantiaceaB,  498. 

Fig-Marigold  Family,  394. 

Marsileae,  495. 

Masked,  288. 

Medullary  rays,  115. 

Medullary  sheath,  116. 

MelanospermesB,  503. 

MelanthacesB,  488. 

Melanthiese,  489. 

Melastoraaceae,  416. 

Meliacese,  397. 

Membranaceous,  >  of  the   texture    of 

Membranous,       5      membrane. 

Menispermaceae,  379. 

Menyanthideae,  454. 

Merenchyma,  43. 

Mericarp,  327. 

MesembryanthemacecB,  394. 

Mesophlaeum,  119. 

Metamorphosed  leaves,  237. 

Metamorphosis,  233. 

Mezereum  Family,  464. 

Micropyle,  310. 

Midrib,  162. 

Mignonette  Family,  387. 

Milkweed  Family,  455. 

Milkwort  Family,  408. 

Mimosae,  410. 

Mint  Family,  447. 

Mistletoe  Family,  466. 

Mitriform,  497. 

Mock  Orange  Family,  423. 

Modified  leaves,  237. 

Mollugineae,  393. 

Monadeiphia,  357. 

Monadelphous,  257,  290. 

Monandria,  357. 

Monandrous,  290. 

Monochlamydeous,  264. 

Monocotyledonous,  334. 

Monocotyledonous  plants,  114,  477. 

Moncecia,  358,  361. 

Monoecious,  266. 

Monogamia,  361. 

Monogynia,  360. 

Monogynous,  297. 

Monopetalae,  367. 

Monopetalous,  256. 

Monopetalous  plants,  426. 

Monophyllous,  285. 

Monosepalous,  256. 

Monotropeae,  438. 

Monstrous,  233. 

Moonseed  Family,  379. 

Moreae,  474. 

Morphology,  14. 

Mosses,  496. 

Mould,  68,  502. 


Mucilaginous,  332. 

Mucronate,  168. 

Mulberry  Family,  474. 

Multifid,  166. 

Multilocular,  302. 

Multiple  fruits,  328. 

Multiplication,  245. 

Multiplication  of  cells,  29. 

Muricate ;    clothed    with    short    and 

hard  points, 
MusaceaB,  485. 
Musci,  361,  496. 
Mushrooms,  500. 
Mustard  Family,  385. 
Mycelium,  500. 
Myricaceae,  472. 
Myristicaceae,  379. 
Myrsinaceae,  440. 
MyrtaceaB,  415. 
Myrtle  Family,  415. 
Naiadaceae,  482. 
Napiform ;   turnip-shaped,  86. 
Nasturtium  Family,  400. 
Natant;  swimming. 
Natural  system,  361. 
Navicular ;  boat-shaped. 
Nectaries,  275,  289. 
Nelumbiaceae,  382. 
Nelumbo  Family,  382. 
Nerved,  161. 
Netted-veined,  161. 
Nettle  Family,  474. 
Neutral,  433. 
Nightshade  Family,  453. 
Nodes,  94. 
Nomenclature,  367. 
Normal ;    agreeing  with   the  pattern 

or  type. 
Nucleus,  28,  310,  329. 
Nucules  ;  little  nuts,  or  nuts  like  en- 

docarps. 
Nut,  327. 

Nutrition  of  plants,  181. 
Nyctaginaceae,  461. 
Nymphaeaceae,  383. 
NyssacesB,  465. 
Oak  Family,  471. 
Obcordate,  168. 
Oblique,  170. 
Oblong,  163. 
Obolariae,  454. 
Obovate,  163. 
Obtuse,  167. 
Ob  volute,  152. 
Ochnaceae,  402. 
Octanclria,  357. 
Octandrous,  290. 
Octogynia,  360. 
Octogynous,  297. 
Offset,  105. 
Oleaceae,  457. 
Oleaster  Family,  464.  / 


516 


INDEX  AND   GLOSSARY 


Onagracese,  416. 

Operculum,  497. 

Opposed,  241. 

Opposite,  140. 

Orange  Family,  397. 

Orchidaceaj,  483. 

Orchis  Family,  483. 

Orders,  353. 

Ordinal  character,  355. 

Ordinary  leaves,  151. 

Organic  constituents,  184. 

Organization,  17. 

Organogeny,  277. 

Organography,  14. 

Organs  of  plants,  64. 

Organs  of  reproduction,  79,  209. 

Organs  of  vegetation,  76, 79. 

Origin  of  the  wrood,  131. 

Orobanchaceae,  443. 

Orpine  Family,  421. 

Orthotropous,  311. 

Osmundineae,  495. 

Outer  suture,  298. 

Oval,  163. 

Ovary,  229,  297. 

Ovate,  163. 

Ovules,  75,  229,  299,  309. 

Ovuliferous,  305. 

Oxalic  acid,  61. 

OxalidaceaB,  400. 

Palate,  288. 

Palese,  220,  433,  491. 

Palmate,  167. 

Palmately  cleft,  167. 

Palmately  divided,  167. 

Palmately  parted,  167. 

Palmately  veined,  163. 

Palme®,  479. 

Palms,  479. 

Panicle,  221. 

PapaveracesB,  383. 

Papayacese,  420. 

Papilionaceae,  409. 

Papilionaceous,  260,  287. 

Pappus,  263,  326. 

Parallel-veined,  161. 

Paraphyses,  497. 

Parasites,  90. 

Parasitic  plants,  90. 

Parenchyma,  43. 

Parietal,  303. 

Parietal  placentation,  302. 

Parnassieae,  389. 

Parsley  Family,  423. 

Parted,  166,  257. 

Partial  petiole,  170. 

PassifloracesB,  419. 

Passion-flower  Family,  419. 

Pear  Family,  413. 

Pectinate,  166. 

Pectine,  59. 

Pedate,  167. 


Pedicels,  216. 
Peduncle,  215,216. 
Peloria,  288. 
Peltate,  164,  312. 
Pendulous,  309. 
Pentadelphous,  290. 
Pentagynia,  360. 
Pentagynous,  297. 
Pentamerous,  241 
Penlandria,  357. 
Pentandrous,  290. 
Pentaphyllous,  285. 
Pentasepalous,  285. 
Pentaslichous,  143. 
Pepo,  327. 
Pepper  Family,  468. 
Pepperwort  Family,  495. 
Perennial  roots,  86. 
Perfoliate,  174. 
Perianth,  228. 
Perianthium,  228. 
Pericarp,  320. 
Perich8etal,497. 
Perigonial,  497. 
Perigonium,*228. 
Perigynous,'259,  290. 
Perisperm,  331. 
Peristome,  497. 
Permeability,  34. 
Persistent,  176,  289. 
Personate,  288. 
Peruvian  Bark  Family,  430. 
Petaloid,  263. 
Petals,  228. 
Petiole,  152,  171. 
Petiolula,  170. 
Petiolulate,  170. 
PhEenogamous,  371. 
Phaenogamous  plants, "75,  371, 
PhiladelphejE,  423. 
Phrymaeeae,  447. 
Phylla,  285. 
Phyllodia,  172. 
Phyllodium,  173. 
Phyllotaxis,  140. 
Physiological  Botany,  14,  17. 
Phytolaccaceee,  460. 
Phytons,  139. 
Phytozoa,  42. 

Pickerel-weed  Family,  488. 
Pilous,  485. 

Pine-Apple  Family,  485. 
Pine  Family,  476. 
Pink  Family,  391. 
Pinnae,  170. 
Pinnate,  168. 
Pinnately  cleft,  166, 
Pinnately  divided,  166. 
Pinnately  parted,  166. 
Pinnately  trifoliolate,  169. 
Pinnately-veined,  162. 
Pinnatifid,  166. 


OF   BOTANICAL    TERMS. 


517 


Piperacese,  468. 
Pipewort  Family,  490. 
Pistillate,  264. 
Pistillidia,  496. 
Pistils,  228,  297. 
Pitchers,  173. 
Pith,  116. 
Pitted  tissue,  48. 
Placenta,  300. 
Placentation,  302. 
Plaited,  151. 
Plane-tree  Family,  474. 
Plantaginaceae,  441. 
Plantain  Family,  441. 
Plantlets,  139. 
Platanaceae,  474. 
Pleurenchyma,  44. 
Plicate,  151. 
Plumbaginaceae,  442. 
Plum  Family,  412. 
Plumule,  334. 
Podosperm,  309. 
Podostemaceae,  469. 
Pointed,  168. 
Pokeweed  Family,  460. 
PolemoniacesB,  450. 
Polemonium  Family,  450. 
Pollen,  228,291,295. 
Pollinia,  295,  484. 
Polyadelphia,  358. 
Polyadelphous,  257,  290. 
Polyandria,  357. 
Polyandrous,  249,  290. 
Polycotyledonous,  336. 
Polygalaceae,  408. 
Polygamia,  358. 
Polygamia  iEqualis,  360. 
Polygamia  Frustranea,  361. 
Polygamia  Necessaria,  361. 
Polygamia  Superfiua,  360. 
Polygamous,  266. 
Polygonaceae,  462. 
Polygynia,  360. 
Polygynous,  297. 
Polype talae,  367.. 
Polypetalous,  257. 
Polypetalous  plants,  371. 
Polyphyllous,  286. 
Polypodineae,  494. 
Polysepalous,  2-57,  286. 
Pome,  327. 
Pomese,  413. 
Pond-weed  Family,  482. 
Pontederiaceae,  488. 
Poppy  Family,  383. 
Porous  cells,  48. 
Porous  vessels,  48. 
Portulacaceae,  393. 
Posterior,  243,  298. 
Praefloration,  278. 
Praefoliation,  151. 
Prickles,  55. 

44 


Prickly- Ash  Family,  401. 

Primary  axis,  216. 

Primary  root,  80. 

Primine,  310. 

Primordial,  151. 

Primulaceae,  440. 

Propagation  from  buds,  103. 

Proper  juices,  57. 

Prosenchyma,  44. 

Protecting  organs,  229. 

Proteine,  28,  200. 

Protoplasm,  201. 

Pulse  Family,  409. 

Purslane  Family,  393. 

Putamen,  322. 

Pyrola  Family,  437. 

Pyroleae,  437. 

Pyxidium,  328. 

Pyxis,  328. 

Quadrangular,  302. 

Gluillwort  Family,  495. 

Quinary,  241. 

Quinate,  169. 

Quincuncial,  143,  280. 

Quinquelocular,  302. 

Quintuple-ribbed,  162. 

Quintupli-nerved,  162. 

Raceme,  217. 

Races,  351. 

Rachis,  216. 

Radiate  ;  diverging  from  a  centre  ;  or 

furnished  with  ray-flowers. 
Radiated-veined,  163. 
Radical,  150. 
Radical  peduncle,  226. 
Radicle,  77,  317,  334. 
Rafflesiaceaj,  460. 
Rameal,  150. 
Ramification,  98. 
RanunculaceaB,  376. 
Raphe,  311. 
Raphides,  62. 

Ray-flowers,  or  rays,  265, 433. 
Receptacle,  219,  229. 
Receptacles  of  secretions,  54. 
Reclinate,  151. 
Reduplicate,  279,  284. 
Reniform,  164. 
Repand,  166. 
Replum,  324. 
Reproduction,  21,  69. 
Resedaceae,  387 
Rest  of  plants,  213. 
Reticulated  leaves,  161. 
Reticulated  ducts,  49. 
Retrograde  metamorphosis,  234. 
Retrorse ;  bent  backwards. 
Retuse,  168. 
Revolute,  151. 
RhamnaceaB,  406. 
Rhatany  Family,  409. 
Rhizanthea3,  460. 


518 


INDEX   AND   GLOSSARY 


Rhizoma,  107. 

Rhizophoraceae,  416. 

RhodospermeaB,  503. 

Rhomboid  ;  oval,  and  a  little  angular 

in  the  middle. 
Ribs,  152, 162. 
Ricciaceae,  497. 
Ringent,  288. 
Ripening,  321. 
Rise  of  sap,  179. 
River-weed  Family,  469. 
Rock-Rose  Family,  389. 
Rosacea^,  411. 
Rosaceous,  287. 
Root,  80. 

Rootlets  ;  ramifications  of  the  root. 
Rootslock,  107. 
Rose  Family,  411. 
Rostrate ;  beaked. 
Rostellate  ;  with  a  small  beak. 
Rosulate  ;  in  a  rosette. 
Rotate,  288. 
Rubiaceae,  429. 
Rudimentary,  291. 
Rue  Family,  401. 
Rugose  ;  wrinkled. 
Ruminated,  332. 
Runcinate,  166. 
Runner,  105. 
Rush  Family,  489. 
Rutaceas,  401. 
Saccate,  288. 
Sagittate,  164. 
SalicaceeB,  473. 
Salver-shaped,  288. 
SalviniesB,  495. 
Samara,  327. 

Sandal-wood  Family,  465. 
SantalacesB,  465. 
Sap,  56, 194. 
Sapindacese,  405. 
Sapodilla  Family,  448. 
Sapotacese,  440. 
Sap-wood,  124. 
Sarcocarp,  322. 
Sarraceniaceae,  383. 
Saururaceas,  467. 
Saxifragaceae,  422. 
Saxifrage  Family,  422. 
Scalariform  ducts,  49. 
Scale-like  hairs,  55. 
Scales,  433. 
Scaly  buds,  96. 
Scape,  226. 

Scarious ;  dry,  thin,  and  colorless. 
Schizandreae,  378. 
Sclerantheae,  393. 
Sclerogen,  37. 
Scorpioid,  225. 

Scrophulariaceae,  445. 

Scurf,  55. 

Seaweeds,  502. 


Secondary  axes,  216. 

Secondary  roots,  85,  87. 

Secondary  spirals,  145. 

Secund  ;  turned  to  one   side,  as  the 

flowers  of  some  spikes,  «&c. 
Secundine,  310. 
Sedge  Family,  490. 
Seed,  329. 

Seed-leaves,  77, 333. 
Segments,  166,  286. 
Seminal,  151. 

Sensitiveness  of  plants,  346. 
Sepals,  228. 
Separated,  264. 
Septicidal,  323. 
Septifragal,  324. 
Serrate,  165. 
Sesameae,  444. 
Sesamum  Family,  444. 
Sessile,  152,215,  291. 
Setae,  55. 
Sheath,  172. 
Shield-shaped,  164. 
Shrubs,  103. 
Signs,  505. 
Sileneae,  392. 
Silex,  63. 
Silicle,  328. 
Siliculosa,  360. 
Silique,  328. 
Siliquosa,  360. 
Silky ;    clothed  with   a  shining    ap- 

fjressed  pubescence, 
ver-grain,  118. 
Simarubaceae,  402. 
Sinuate,  166. 
Sinus,  163. 
Sleep  of  plants,  342. 
SmilaceaB,  487. 
Smilax  Family,  487. 
Soapberry  Family,  405. 
Solanaceae,  453. 
Sori,  494. 
Spadix,  218. 
Spathe,  218. 
Spatulate ;    oblong   or  obovate,   with 

the  lower  end  much  narrowed. 
Specialized  cell,  53. 
Species,  21, 350. 
Specific  character,  355. 
Spermoderm,  329. 
Spiderwort  Family,  490. 
Spigelieae,  431. 
Spike,  218. 

Spikenard  Family,  425. 
Spindle-tree  Family,  406. 
Spine,  105. 

Spinose  ;  furnished  with  spines. 
Spiral  ducts,  50. 
Spirally,  280. 
Spiral  markings,  41. 
Spiral  vessels,  50. 


OF    BOTANICAL    TERMS. 


519 


Spongioles  or  Spongelets,  82. 
Sporangia,  72,  494. 
Spores,  69,  339,  493. 
Spore-cases,  72. 
Sporidia,  500. 
Sporocarp,  495. 
Sporules,  69,  500. 
Spur,  288. 

Spurge  Family,  469. 
Squamellae,  or  Squamulse,  491. 
Squamellate ;  bearing  small  scales. 
Squarrose  ;  spreading  at  right  angles 
or  more  in  all   directions  from    a 
common  axis. 
Stamens,  228,  289. 
Staminate,  264. 
Staminodium,  275. 
Standard,  261. 
StaphyleaceaB,  407. 
Starch,  57, 198. 

Stellate ;  in  star-shaped  whorls. 
Stellatese,  429. 
Stem,  93. 
Sterile,  264,  290. 
Stigma,  229,  297,299. 
Stigmatic,  299. 
Stigmatiferous,  305. 
Stings,  55. 
Stipe,  277. 
Stipellate,  175. 
Stipelles,  175. 
Stipes,  500. 
Stipitate,  277. 
Stipulate,  175. 
Stipules,  174. 

St  John's-wort  Family,  390. 

Stolon,  104. 

Stoloniferous,  104. 

Stomates  or  Stomata,  55,  157. 

Storax  Family,  440. 

Striate ;  marked  with  longitudinal 
lines  or  stripes. 

Strobile,  329. 

Strophiole,  331. 

Structural  Botany,  14,  17. 

Structure  of  the  flower,  230. 

Style,  229,  297. 

Styracaceae,  440. 

Sub ;  a  prefix  of  qualification  ;  thus, 
subcordate  means  slightly  cordate  } 
subovate,  somewhat  ovate,  &c. 

Subclasses,  354. 

Suborders,  354. 

Subgenera,  353. 

Subulate  ;  awl-shaped  ;  tapering  to  a 
sharp  point  from  a  broader  base. 

Succulose ;  bearing  suckers,  105. 

Sucker,  105. 

SuflTrutescent ;  scarcely  shrubby,  103. 

Suffruticose  ;  somewhat  shrubby,  103. 

Sugar,  60. 

Sulcate ;  grooved. 


Sundew  Family,  388. 
Sunflower  Family,  432. 
Superior,  243,  260,  335. 
Supervolutive,  284. 
Suppression,  246,  263. 
Suspended,  309. 
Suspensor,  317. 
Suture,  292. 

Sweet-Gale  Family,  472. 
Sweet-Gum  Family,  474. 
Symmetrical  flower,  238. 
Syncarpous,  258,  300. 
Syngenesia,  358. 
Syngenesious,  257,  29^. 
Systematic  Botany,  15,  349. 
Tamariscineee,  391. 
Tap-root,  84. 
Taxineae,  476. 
Tea  Family,  397. 
Teasel  Family,  432. 
Tendril,  105. 
Terminal,  225. 
Terminal  bud,  95. 
Terminology,  15. 
Ternale,  169. 
Ternstroemiaceae,  397. 
Testa,  310,  329. 
Tetradynamia,  357. 
Tetradynamous,  250, 290. 
Tetragynia,  360. 
Tetragynous,  297. 
Tetrandria,  357. 
Tetrandrous,  290. 
Tetraphyllous,  285. 
Tetrasepalous,  285. 
Thallophytes,  73,  365,  498. 
Thallus,  71,  365. 
Thecse,  291. 
Thecapbore,  277. 
Thorn,  105, 
Three-ranked,  142. 
Thymelaceae,  464. 
Thyrsus,  222. 
Tiliaceae,  395. 
Toothed,  166,  257. 
Toothings,  165. 
Torus,  229: 
Tracheae,  50. 
Trachenchyma,  49. 
Transverse,  312, 324. 
Trees   104. 

Triadelphous,  257, 290. 
Triandria,  357. 
Triandrous,  290. 
Tribes,  354. 
Tricoccous,  323. 
Trifid,  166. 
Trigynia,  360. 
Trigynous,  2.97. 
Trilliaceae,  487. 
Trilocular,  302. 
Trimerous,  241. 


520 


INDEX   AND   GLOSSARY. 


Trioecia,  361. 

Triphyllous,  285. 

Tripinnate,  170. 

Tripinnatifid,  167. 

Triple-ribbed,  162. 

Tripli-nerved,  162. 

Trisepalous,  285. 

Trislichous,  142. 

Triternate,  170. 

Tropaeolaceae,  400. 

Truncate,  168. 

Tube,  278,286. 

Tuber,  108. 

Tubular,  288. 

Tubuliflorse,  433. 

Tufted,  ]50. 

Tupelo  Family,  465. 

Turbinate ;  top-shaped,  inversely  con- 

Turneraceae,  419.  [ical. 

Two-ranked,  142. 

Type,  229,  350. 

Typhaceae,  481. 

Ulmaceae,  466. 

Umbel,  217., 

Umbellets,  221. 

Umbel liferae,  423. 

Umbilicate  ;  depressed  in  the  centre. 

Unarmed  ;  not  prickly. 

Uncinate  ;  hooKed. 

Undershrubs,  103. 

Unguis,  286. 

Unijugate,  170. 

Unilateral ;  one-sided. 

Unisexual,  264. 

Unlining,  249,  253. 

Urticaceai,  474. 

UrticesB,  475. 

Utricle,  327. 

Uvularieae,  489. 

Vaccinieae,  436. 

Vaginula,  497. 

Vague,  335. 

ValerianacesB,  431. 

Valerian  Family,  431. 

Valvate,  151,  284. 

Valves,  323 

Valvular,  284. 

Varieties,  351. 

Vascular  plants,  73,  364. 

Vascular  tissue,  48. 

Vasiform  tissue,  48. 

Vegetable  acids,  61,  200. 

Vegetable  digestion,  194. 

Vegetable  jelly,  59. 

Vegetable  mucilage,  60,  197. 

Veinlets,  162. 


Veins,  152. 

Venation,  161. 

Ventral  suture,  298. 

Verbenaceae,  446. 

Vernation,  151,279. 

Versatile,  292. 

Vertical  leaves,  170. 

Vertical  system,  48,  53, 113. 

Verticil,  94,  141. 

Verticillaster,  226. 

Verticillate,  141,  226. 

Vervain  Family,  446. 

Vessels,  48. 

Vexillary,  282. 

Vexillum,  261. 

Villous,    or    Villose ;    clothed    with 

long  and  shaggy  hairs. 
Vinejamily,  407. 
Violaceae,  387. 
Violet  Family,  387. 
Vitaceas,  407. 
Voluble ;  twining. 
Volva,  500. 
Walnut  Family,  471. 
Water-leaf  Family,  449. 
Water-Lily  Family,  383. 
Water-Pitcher  Family,  383. 
Water-Plantain  Family,  482. 
Water-shield  Family,  381. 
Water-Star  wort  Family,  468. 
Waterwort  Family,  391. 
Wax,  60. 

Wheel-shaped,  288. 
Whorl,  94,  141. 
Whorled,  141,  226. 
Whortleberry  Family,  436. 
Willow  Family,  473. 
Winged,  172. 
Wings,  261. 
Wintereae,  378. 
Winter's-Bark  Family,  378. 
Witch-Hazel  Family,  423. 
Wood,  117. 

Wood-Sorrel  Family,  400. 
Woody,  152. 
Woody  fibre,  44. 
Woody  tissue,  44. 
Woolly;  clothed  with  long,  matted 

hairs. 
Wrapper,  500. 
XyridacesB,  490. 
Yam  Family,  487. 
Yew  Family,  476. 
Zanthoxylaceae,  401. 
Zingiberaceae,  484. 
Zygophyllaceae,  400. 


THE   END. 


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